diff --git a/.travis.yml b/.travis.yml
index c66632c..4f1272f 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -18,6 +18,7 @@ env:
   - TOX_ENV=system-tests
   - TOX_ENV=system-tests3
   - TOX_ENV=gae
+  - TOX_ENV=flake8
   global:
   - GAE_PYTHONPATH=${HOME}/.cache/google_appengine
 cache:
diff --git a/docs/conf.py b/docs/conf.py
index f84911c..fcbf2fb 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -5,14 +5,22 @@
 #
 
 import os
-from pkg_resources import get_distribution
 import sys
 
-import mock
 
-# See
-# (https://read-the-docs.readthedocs.io/en/latest/faq.html#\
-#  i-get-import-errors-on-libraries-that-depend-on-c-modules)
+# In order to load django before 1.7, we need to create a faux
+# settings module and load it. This assumes django has been installed
+# (but it must be for the docs to build), so if it has not already
+# been installed run `pip install -r docs/requirements.txt`.
+os.environ['DJANGO_SETTINGS_MODULE'] = 'tests.contrib.test_django_settings'
+import django
+import mock
+from pkg_resources import get_distribution
+if django.VERSION[1] < 7:
+    sys.path.insert(0, '.')
+
+# See https://read-the-docs.readthedocs.io/en/latest/faq.html#i-get-import-errors-on-libraries-that-depend-on-c-modules
+
 
 class Mock(mock.Mock):
 
@@ -61,15 +69,6 @@ release = distro.version
 
 exclude_patterns = ['_build']
 
-# In order to load django before 1.7, we need to create a faux
-# settings module and load it. This assumes django has been installed
-# (but it must be for the docs to build), so if it has not already
-# been installed run `pip install -r docs/requirements.txt`.
-os.environ['DJANGO_SETTINGS_MODULE'] = 'tests.contrib.test_django_settings'
-import django
-if django.VERSION[1] < 7:
-    sys.path.insert(0, '.')
-
 # -- Options for HTML output ----------------------------------------------
 
 # We fake our more expensive imports when building the docs.
diff --git a/oauth2client/_helpers.py b/oauth2client/_helpers.py
index 39bfeb6..2b86d01 100644
--- a/oauth2client/_helpers.py
+++ b/oauth2client/_helpers.py
@@ -15,6 +15,7 @@
 
 import base64
 import json
+
 import six
 
 
diff --git a/oauth2client/_openssl_crypt.py b/oauth2client/_openssl_crypt.py
index 7a76fb7..49b763b 100644
--- a/oauth2client/_openssl_crypt.py
+++ b/oauth2client/_openssl_crypt.py
@@ -13,8 +13,6 @@
 # limitations under the License.
 """OpenSSL Crypto-related routines for oauth2client."""
 
-import base64
-
 from OpenSSL import crypto
 
 from oauth2client._helpers import _parse_pem_key
diff --git a/oauth2client/_pycrypto_crypt.py b/oauth2client/_pycrypto_crypt.py
index 5ee7046..0b31ba3 100644
--- a/oauth2client/_pycrypto_crypt.py
+++ b/oauth2client/_pycrypto_crypt.py
@@ -13,8 +13,8 @@
 # limitations under the License.
 """pyCrypto Crypto-related routines for oauth2client."""
 
-from Crypto.PublicKey import RSA
 from Crypto.Hash import SHA256
+from Crypto.PublicKey import RSA
 from Crypto.Signature import PKCS1_v1_5
 from Crypto.Util.asn1 import DerSequence
 
diff --git a/oauth2client/client.py b/oauth2client/client.py
index 432146e..fafa8c0 100644
--- a/oauth2client/client.py
+++ b/oauth2client/client.py
@@ -17,33 +17,32 @@
 Tools for interacting with OAuth 2.0 protected resources.
 """
 
-import base64
 import collections
 import copy
 import datetime
 import json
 import logging
 import os
+import shutil
 import socket
 import sys
 import tempfile
-import time
-import shutil
+
+import httplib2
 import six
 from six.moves import http_client
 from six.moves import urllib
 
-import httplib2
+from oauth2client import clientsecrets
 from oauth2client import GOOGLE_AUTH_URI
 from oauth2client import GOOGLE_DEVICE_URI
 from oauth2client import GOOGLE_REVOKE_URI
-from oauth2client import GOOGLE_TOKEN_URI
 from oauth2client import GOOGLE_TOKEN_INFO_URI
+from oauth2client import GOOGLE_TOKEN_URI
+from oauth2client import util
 from oauth2client._helpers import _from_bytes
 from oauth2client._helpers import _to_bytes
 from oauth2client._helpers import _urlsafe_b64decode
-from oauth2client import clientsecrets
-from oauth2client import util
 
 
 __author__ = 'jcgregorio@google.com (Joe Gregorio)'
@@ -259,8 +258,8 @@ class Credentials(object):
             strip: array, An array of names of members to exclude from the
                    JSON.
             to_serialize: dict, (Optional) The properties for this object
-                          that will be serialized. This allows callers to modify
-                          before serializing.
+                          that will be serialized. This allows callers to
+                          modify before serializing.
 
         Returns:
             string, a JSON representation of this instance, suitable to pass to
@@ -359,7 +358,8 @@ class Storage(object):
 
         Args:
             lock: An optional threading.Lock-like object. Must implement at
-                  least acquire() and release(). Does not need to be re-entrant.
+                  least acquire() and release(). Does not need to be
+                  re-entrant.
         """
         self._lock = lock
 
@@ -1195,7 +1195,7 @@ class GoogleCredentials(OAuth2Credentials):
         print(response)
     """
 
-    NON_SERIALIZED_MEMBERS =  (
+    NON_SERIALIZED_MEMBERS = (
         frozenset(['_private_key']) |
         OAuth2Credentials.NON_SERIALIZED_MEMBERS)
     """Members that aren't serialized when object is converted to JSON."""
@@ -1253,12 +1253,11 @@ class GoogleCredentials(OAuth2Credentials):
         # We handle service_account.ServiceAccountCredentials since it is a
         # possible return type of GoogleCredentials.get_application_default()
         if (data['_module'] == 'oauth2client.service_account' and
-            data['_class'] == 'ServiceAccountCredentials'):
+                data['_class'] == 'ServiceAccountCredentials'):
             return ServiceAccountCredentials.from_json(data)
         elif (data['_module'] == 'oauth2client.service_account' and
-              data['_class'] == '_JWTAccessCredentials'):
+                data['_class'] == '_JWTAccessCredentials'):
             return _JWTAccessCredentials.from_json(data)
-        
 
         token_expiry = _parse_expiry(data.get('token_expiry'))
         google_credentials = cls(
@@ -1468,8 +1467,7 @@ def save_to_well_known_file(credentials, well_known_file=None):
 
 def _get_environment_variable_file():
     application_default_credential_filename = (
-      os.environ.get(GOOGLE_APPLICATION_CREDENTIALS,
-                     None))
+        os.environ.get(GOOGLE_APPLICATION_CREDENTIALS, None))
 
     if application_default_credential_filename:
         if os.path.isfile(application_default_credential_filename):
@@ -1552,8 +1550,8 @@ def _raise_exception_for_reading_json(credential_file,
                                       extra_help,
                                       error):
     raise ApplicationDefaultCredentialsError(
-      'An error was encountered while reading json file: ' +
-      credential_file + extra_help + ': ' + str(error))
+        'An error was encountered while reading json file: ' +
+        credential_file + extra_help + ': ' + str(error))
 
 
 def _get_application_default_credential_GAE():
@@ -2213,7 +2211,8 @@ def flow_from_clientsecrets(filename, scope, redirect_uri=None,
     except clientsecrets.InvalidClientSecretsError as e:
         if message is not None:
             if e.args:
-                message = 'The client secrets were invalid: \n{0}\n{1}'.format(e, message)
+                message = ('The client secrets were invalid: '
+                           '\n{0}\n{1}'.format(e, message))
             sys.exit(message)
         else:
             raise
diff --git a/oauth2client/clientsecrets.py b/oauth2client/clientsecrets.py
index 4a47d0d..2c69d7e 100644
--- a/oauth2client/clientsecrets.py
+++ b/oauth2client/clientsecrets.py
@@ -19,8 +19,8 @@ an OAuth 2.0 protected service.
 """
 
 import json
-import six
 
+import six
 
 __author__ = 'jcgregorio@google.com (Joe Gregorio)'
 
diff --git a/oauth2client/contrib/_fcntl_opener.py b/oauth2client/contrib/_fcntl_opener.py
index 4e758b9..9edfec2 100644
--- a/oauth2client/contrib/_fcntl_opener.py
+++ b/oauth2client/contrib/_fcntl_opener.py
@@ -13,9 +13,8 @@
 # limitations under the License.
 
 import errno
-import time
-
 import fcntl
+import time
 
 from oauth2client.contrib.locked_file import _Opener
 from oauth2client.contrib.locked_file import AlreadyLockedException
diff --git a/oauth2client/contrib/_metadata.py b/oauth2client/contrib/_metadata.py
index 2995f65..07ca619 100644
--- a/oauth2client/contrib/_metadata.py
+++ b/oauth2client/contrib/_metadata.py
@@ -18,15 +18,15 @@ See https://cloud.google.com/compute/docs/metadata
 """
 
 import datetime
-import httplib2
 import json
 
+import httplib2
 from six.moves import http_client
 from six.moves.urllib import parse as urlparse
 
+from oauth2client import util
 from oauth2client._helpers import _from_bytes
 from oauth2client.client import _UTCNOW
-from oauth2client import util
 
 
 METADATA_ROOT = 'http://metadata.google.internal/computeMetadata/v1/'
diff --git a/oauth2client/contrib/appengine.py b/oauth2client/contrib/appengine.py
index 84c3a39..746312a 100644
--- a/oauth2client/contrib/appengine.py
+++ b/oauth2client/contrib/appengine.py
@@ -24,19 +24,18 @@ import os
 import pickle
 import threading
 
-import httplib2
-import webapp2 as webapp
-
 from google.appengine.api import app_identity
 from google.appengine.api import memcache
 from google.appengine.api import users
 from google.appengine.ext import db
 from google.appengine.ext.webapp.util import login_required
+import httplib2
+import webapp2 as webapp
 
+from oauth2client import clientsecrets
 from oauth2client import GOOGLE_AUTH_URI
 from oauth2client import GOOGLE_REVOKE_URI
 from oauth2client import GOOGLE_TOKEN_URI
-from oauth2client import clientsecrets
 from oauth2client import util
 from oauth2client.client import AccessTokenRefreshError
 from oauth2client.client import AssertionCredentials
diff --git a/oauth2client/contrib/devshell.py b/oauth2client/contrib/devshell.py
index 662cb70..b489c10 100644
--- a/oauth2client/contrib/devshell.py
+++ b/oauth2client/contrib/devshell.py
@@ -19,8 +19,8 @@ import json
 import os
 import socket
 
-from oauth2client._helpers import _to_bytes
 from oauth2client import client
+from oauth2client._helpers import _to_bytes
 
 # Expose utcnow() at module level to allow for
 # easier testing (by replacing with a stub).
diff --git a/oauth2client/contrib/django_orm.py b/oauth2client/contrib/django_orm.py
index 18e24f2..205daac 100644
--- a/oauth2client/contrib/django_orm.py
+++ b/oauth2client/contrib/django_orm.py
@@ -21,13 +21,13 @@ the Django datastore.
 Only Django versions 1.8+ are supported.
 """
 
-import oauth2client
 import base64
 import pickle
-import six
 
 from django.db import models
 from django.utils.encoding import smart_bytes, smart_text
+
+import oauth2client
 from oauth2client.client import Storage as BaseStorage
 
 
@@ -179,4 +179,4 @@ class Storage(BaseStorage):
         """Delete Credentials from the datastore."""
 
         query = {self.key_name: self.key_value}
-        entities = self.model_class.objects.filter(**query).delete()
+        self.model_class.objects.filter(**query).delete()
diff --git a/oauth2client/contrib/django_util/__init__.py b/oauth2client/contrib/django_util/__init__.py
index 5aa12ac..4718da2 100644
--- a/oauth2client/contrib/django_util/__init__.py
+++ b/oauth2client/contrib/django_util/__init__.py
@@ -15,10 +15,10 @@
 """Utilities for the Django web framework
 
 Provides Django views and helpers the make using the OAuth2 web server
-flow easier. It includes an ``oauth_required`` decorator to automatically ensure
-that user credentials are available, and an ``oauth_enabled`` decorator to check
-if the user has authorized, and helper shortcuts to create the authorization
-URL otherwise.
+flow easier. It includes an ``oauth_required`` decorator to automatically
+ensure that user credentials are available, and an ``oauth_enabled`` decorator
+to check if the user has authorized, and helper shortcuts to create the
+authorization URL otherwise.
 
 Only Django versions 1.8+ are supported.
 
@@ -89,8 +89,8 @@ Add the oauth2 routes to your application's urls.py urlpatterns.
    urlpatterns += [url(r'^oauth2/', include(oauth2_urls))]
 
 To require OAuth2 credentials for a view, use the `oauth2_required` decorator.
-This creates a credentials object with an id_token, and allows you to create an
-`http` object to build service clients with. These are all attached to the
+This creates a credentials object with an id_token, and allows you to create
+an `http` object to build service clients with. These are all attached to the
 request.oauth
 
 .. code-block:: python
@@ -124,8 +124,9 @@ To make OAuth2 optional and provide an authorization link in your own views.
            return HttpResponse("User email: %s"
             % request.oauth.credentials.id_token['email'])
        else:
-           return HttpResponse('Here is an OAuth Authorize link:
-           <a href="%s">Authorize</a>' % request.oauth.get_authorize_redirect())
+           return HttpResponse(
+               'Here is an OAuth Authorize link: <a href="%s">Authorize</a>'
+                % request.oauth.get_authorize_redirect())
 
 If a view needs a scope not included in the default scopes specified in
 the settings, you can use [incremental auth](https://developers.google.com/identity/sign-in/web/incremental-auth)
@@ -144,8 +145,9 @@ and specify additional scopes in the decorator arguments.
            events = service.files().list().execute()['items']
            return HttpResponse(str(events))
        else:
-           return HttpResponse('Here is an OAuth Authorize link:
-           <a href="%s">Authorize</a>' % request.oauth.get_authorize_redirect())
+           return HttpResponse(
+               'Here is an OAuth Authorize link: <a href="%s">Authorize</a>'
+                % request.oauth.get_authorize_redirect())
 
 
 To provide a callback on authorization being completed, use the
@@ -168,9 +170,10 @@ import django.conf
 from django.core import exceptions
 from django.core import urlresolvers
 import httplib2
+from six.moves.urllib import parse
+
 from oauth2client import clientsecrets
 from oauth2client.contrib.django_util import storage
-from six.moves.urllib import parse
 
 GOOGLE_OAUTH2_DEFAULT_SCOPES = ('email',)
 GOOGLE_OAUTH2_REQUEST_ATTRIBUTE = 'oauth'
@@ -202,9 +205,9 @@ def _get_oauth2_client_id_and_secret(settings_instance):
             return client_id, client_secret
         else:
             raise exceptions.ImproperlyConfigured(
-                "Must specify either GOOGLE_OAUTH2_CLIENT_SECRETS_JSON, or  "
-                " both GOOGLE_OAUTH2_CLIENT_ID and GOOGLE_OAUTH2_CLIENT_SECRET "
-                "in settings.py")
+                "Must specify either GOOGLE_OAUTH2_CLIENT_SECRETS_JSON, or "
+                "both GOOGLE_OAUTH2_CLIENT_ID and "
+                "GOOGLE_OAUTH2_CLIENT_SECRET in settings.py")
 
 
 class OAuth2Settings(object):
@@ -290,8 +293,8 @@ class UserOAuth2(object):
     def has_credentials(self):
         """Returns True if there are valid credentials for the current user
         and required scopes."""
-        return (self.credentials and not self.credentials.invalid
-                and self.credentials.has_scopes(self.scopes))
+        return (self.credentials and not self.credentials.invalid and
+                self.credentials.has_scopes(self.scopes))
 
     @property
     def credentials(self):
diff --git a/oauth2client/contrib/django_util/decorators.py b/oauth2client/contrib/django_util/decorators.py
index 0e0a4b2..26c3216 100644
--- a/oauth2client/contrib/django_util/decorators.py
+++ b/oauth2client/contrib/django_util/decorators.py
@@ -13,9 +13,10 @@
 # limitations under the License.
 
 from django import shortcuts
-from oauth2client.contrib import django_util
 from six import wraps
 
+from oauth2client.contrib import django_util
+
 
 def oauth_required(decorated_function=None, scopes=None, **decorator_kwargs):
     """ Decorator to require OAuth2 credentials for a view
@@ -36,7 +37,7 @@ def oauth_required(decorated_function=None, scopes=None, **decorator_kwargs):
                        developerKey=API_KEY)
           events = service.events().list(
                                     calendarId='primary').execute()['items']
-          return HttpResponse("email: %s , calendar: %s" % (email, str(events)))
+          return HttpResponse("email: %s, calendar: %s" % (email, str(events)))
 
     :param decorated_function: View function to decorate, must have the Django
            request object as the first argument
diff --git a/oauth2client/contrib/django_util/site.py b/oauth2client/contrib/django_util/site.py
index c13ed6b..7943920 100644
--- a/oauth2client/contrib/django_util/site.py
+++ b/oauth2client/contrib/django_util/site.py
@@ -13,6 +13,7 @@
 # limitations under the License.
 
 from django.conf import urls
+
 from oauth2client.contrib.django_util import views
 
 urlpatterns = [
diff --git a/oauth2client/contrib/django_util/views.py b/oauth2client/contrib/django_util/views.py
index 0d5561c..de8df07 100644
--- a/oauth2client/contrib/django_util/views.py
+++ b/oauth2client/contrib/django_util/views.py
@@ -16,9 +16,11 @@ import hashlib
 import json
 import os
 import pickle
+
 from django import http
-from django.core import urlresolvers
 from django import shortcuts
+from django.core import urlresolvers
+
 from oauth2client import client
 from oauth2client.contrib import django_util
 from oauth2client.contrib.django_util import signals
@@ -87,7 +89,8 @@ def oauth2_callback(request):
     try:
         server_csrf = request.session[_CSRF_KEY]
     except KeyError:
-        return http.HttpResponseBadRequest("No existing session for this flow.")
+        return http.HttpResponseBadRequest(
+            "No existing session for this flow.")
 
     try:
         state = json.loads(encoded_state)
diff --git a/oauth2client/contrib/flask_util.py b/oauth2client/contrib/flask_util.py
index fc6dd3d..91bf7b8 100644
--- a/oauth2client/contrib/flask_util.py
+++ b/oauth2client/contrib/flask_util.py
@@ -162,14 +162,11 @@ available outside of a request context, you will need to implement your own
 :class:`oauth2client.Storage`.
 """
 
+from functools import wraps
 import hashlib
 import json
 import os
 import pickle
-from functools import wraps
-
-import six.moves.http_client as httplib
-import httplib2
 
 try:
     from flask import Blueprint
@@ -182,10 +179,13 @@ try:
 except ImportError:  # pragma: NO COVER
     raise ImportError('The flask utilities require flask 0.9 or newer.')
 
+import httplib2
+import six.moves.http_client as httplib
+
+from oauth2client import clientsecrets
 from oauth2client.client import FlowExchangeError
 from oauth2client.client import OAuth2WebServerFlow
 from oauth2client.contrib.dictionary_storage import DictionaryStorage
-from oauth2client import clientsecrets
 
 
 __author__ = 'jonwayne@google.com (Jon Wayne Parrott)'
@@ -446,8 +446,8 @@ class UserOAuth2(object):
         if not self.credentials:
             return False
         # Is the access token expired? If so, do we have an refresh token?
-        elif (self.credentials.access_token_expired
-                and not self.credentials.refresh_token):
+        elif (self.credentials.access_token_expired and
+                not self.credentials.refresh_token):
             return False
         else:
             return True
diff --git a/oauth2client/contrib/gce.py b/oauth2client/contrib/gce.py
index b495e44..cccf495 100644
--- a/oauth2client/contrib/gce.py
+++ b/oauth2client/contrib/gce.py
@@ -112,7 +112,8 @@ class AppAssertionCredentials(AssertionCredentials):
         """
         if self.invalid:
             info = _metadata.get_service_account_info(
-                http_request, service_account=self.service_account_email or 'default')
+                http_request,
+                service_account=self.service_account_email or 'default')
             self.invalid = False
             self.service_account_email = info['email']
             self.scopes = info['scopes']
diff --git a/oauth2client/contrib/multistore_file.py b/oauth2client/contrib/multistore_file.py
index 879f3b6..3c96eb1 100644
--- a/oauth2client/contrib/multistore_file.py
+++ b/oauth2client/contrib/multistore_file.py
@@ -50,12 +50,11 @@ import logging
 import os
 import threading
 
+from oauth2client import util
 from oauth2client.client import Credentials
 from oauth2client.client import Storage as BaseStorage
-from oauth2client import util
 from oauth2client.contrib.locked_file import LockedFile
 
-
 __author__ = 'jbeda@google.com (Joe Beda)'
 
 logger = logging.getLogger(__name__)
diff --git a/oauth2client/contrib/sqlalchemy.py b/oauth2client/contrib/sqlalchemy.py
index 4c62a06..a05a9fe 100644
--- a/oauth2client/contrib/sqlalchemy.py
+++ b/oauth2client/contrib/sqlalchemy.py
@@ -90,9 +90,10 @@ We will reuse tables defined above.
 
 from __future__ import absolute_import
 
-import oauth2client.client
 import sqlalchemy.types
 
+import oauth2client.client
+
 
 class CredentialsType(sqlalchemy.types.PickleType):
     """Type representing credentials.
diff --git a/oauth2client/contrib/xsrfutil.py b/oauth2client/contrib/xsrfutil.py
index 20e728e..91545e7 100644
--- a/oauth2client/contrib/xsrfutil.py
+++ b/oauth2client/contrib/xsrfutil.py
@@ -19,8 +19,8 @@ import binascii
 import hmac
 import time
 
-from oauth2client._helpers import _to_bytes
 from oauth2client import util
+from oauth2client._helpers import _to_bytes
 
 __authors__ = [
     '"Doug Coker" <dcoker@google.com>',
diff --git a/oauth2client/service_account.py b/oauth2client/service_account.py
index ce7f78e..d2b2b0b 100644
--- a/oauth2client/service_account.py
+++ b/oauth2client/service_account.py
@@ -17,27 +17,24 @@
 import base64
 import copy
 import datetime
-import httplib2
 import json
 import time
 
+import httplib2
+
+from oauth2client import crypt
 from oauth2client import GOOGLE_REVOKE_URI
 from oauth2client import GOOGLE_TOKEN_URI
-from oauth2client._helpers import _json_encode
-from oauth2client._helpers import _from_bytes
-from oauth2client._helpers import _urlsafe_b64encode
 from oauth2client import util
+from oauth2client._helpers import _from_bytes
 from oauth2client.client import _apply_user_agent
 from oauth2client.client import _initialize_headers
+from oauth2client.client import _UTCNOW
 from oauth2client.client import AccessTokenInfo
 from oauth2client.client import AssertionCredentials
 from oauth2client.client import clean_headers
 from oauth2client.client import EXPIRY_FORMAT
-from oauth2client.client import GoogleCredentials
 from oauth2client.client import SERVICE_ACCOUNT
-from oauth2client.client import TokenRevokeError
-from oauth2client.client import _UTCNOW
-from oauth2client import crypt
 
 
 _PASSWORD_DEFAULT = 'notasecret'
@@ -94,7 +91,7 @@ class ServiceAccountCredentials(AssertionCredentials):
     MAX_TOKEN_LIFETIME_SECS = 3600
     """Max lifetime of the token (one hour, in seconds)."""
 
-    NON_SERIALIZED_MEMBERS =  (
+    NON_SERIALIZED_MEMBERS = (
         frozenset(['_signer']) |
         AssertionCredentials.NON_SERIALIZED_MEMBERS)
     """Members that aren't serialized when object is converted to JSON."""
@@ -138,8 +135,8 @@ class ServiceAccountCredentials(AssertionCredentials):
             strip: array, An array of names of members to exclude from the
                    JSON.
             to_serialize: dict, (Optional) The properties for this object
-                          that will be serialized. This allows callers to modify
-                          before serializing.
+                          that will be serialized. This allows callers to
+                          modify before serializing.
 
         Returns:
             string, a JSON representation of this instance, suitable to pass to
@@ -502,7 +499,7 @@ class ServiceAccountCredentials(AssertionCredentials):
         result._private_key_pkcs12 = self._private_key_pkcs12
         result._private_key_password = self._private_key_password
         return result
- 
+
     def create_with_claims(self, claims):
         """Create credentials that specify additional claims.
 
@@ -511,7 +508,8 @@ class ServiceAccountCredentials(AssertionCredentials):
 
         Returns:
             ServiceAccountCredentials, a copy of the current service account
-            credentials with updated claims to use when obtaining access tokens.
+            credentials with updated claims to use when obtaining access
+            tokens.
         """
         new_kwargs = dict(self._kwargs)
         new_kwargs.update(claims)
@@ -552,11 +550,11 @@ class ServiceAccountCredentials(AssertionCredentials):
 
 
 def _datetime_to_secs(utc_time):
-   # TODO(issue 298): use time_delta.total_seconds()
-   # time_delta.total_seconds() not supported in Python 2.6
-   epoch = datetime.datetime(1970, 1, 1)
-   time_delta = utc_time - epoch
-   return time_delta.days * 86400 + time_delta.seconds
+    # TODO(issue 298): use time_delta.total_seconds()
+    # time_delta.total_seconds() not supported in Python 2.6
+    epoch = datetime.datetime(1970, 1, 1)
+    time_delta = utc_time - epoch
+    return time_delta.days * 86400 + time_delta.seconds
 
 
 class _JWTAccessCredentials(ServiceAccountCredentials):
@@ -607,7 +605,8 @@ class _JWTAccessCredentials(ServiceAccountCredentials):
             h = credentials.authorize(h)
         """
         request_orig = http.request
-        request_auth = super(_JWTAccessCredentials, self).authorize(http).request
+        request_auth = super(
+            _JWTAccessCredentials, self).authorize(http).request
 
         # The closure that will replace 'httplib2.Http.request'.
         def new_request(uri, method='GET', body=None, headers=None,
@@ -695,7 +694,8 @@ class _JWTAccessCredentials(ServiceAccountCredentials):
 
     def _create_token(self, additional_claims=None):
         now = _UTCNOW()
-        expiry = now + datetime.timedelta(seconds=self._MAX_TOKEN_LIFETIME_SECS)
+        lifetime = datetime.timedelta(seconds=self._MAX_TOKEN_LIFETIME_SECS)
+        expiry = now + lifetime
         payload = {
             'iat': _datetime_to_secs(now),
             'exp': _datetime_to_secs(expiry),
diff --git a/oauth2client/tools.py b/oauth2client/tools.py
index 9e3e85d..499861e 100644
--- a/oauth2client/tools.py
+++ b/oauth2client/tools.py
@@ -27,8 +27,8 @@ import sys
 
 from six.moves import BaseHTTPServer
 from six.moves import http_client
-from six.moves import urllib
 from six.moves import input
+from six.moves import urllib
 
 from oauth2client import client
 from oauth2client import util
@@ -48,6 +48,32 @@ with information from the APIs Console <https://code.google.com/apis/console>.
 
 """
 
+_FAILED_START_MESSAGE = """
+Failed to start a local webserver listening on either port 8080
+or port 8090. Please check your firewall settings and locally
+running programs that may be blocking or using those ports.
+
+Falling back to --noauth_local_webserver and continuing with
+authorization.
+"""
+
+_BROWSER_OPENED_MESSAGE = """
+Your browser has been opened to visit:
+
+    %s
+
+If your browser is on a different machine then exit and re-run this
+application with the command-line parameter
+
+  --noauth_local_webserver
+"""
+
+_GO_TO_LINK_MESSAGE = """
+Go to the following link in your browser:
+
+    %s
+"""
+
 
 def _CreateArgumentParser():
     try:
@@ -182,14 +208,7 @@ def run_flow(flow, storage, flags=None, http=None):
                 break
         flags.noauth_local_webserver = not success
         if not success:
-            print('Failed to start a local webserver listening '
-                  'on either port 8080')
-            print('or port 8090. Please check your firewall settings and locally')
-            print('running programs that may be blocking or using those ports.')
-            print()
-            print('Falling back to --noauth_local_webserver and continuing with')
-            print('authorization.')
-            print()
+            print(_FAILED_START_MESSAGE)
 
     if not flags.noauth_local_webserver:
         oauth_callback = 'http://%s:%s/' % (flags.auth_host_name, port_number)
@@ -201,21 +220,9 @@ def run_flow(flow, storage, flags=None, http=None):
     if not flags.noauth_local_webserver:
         import webbrowser
         webbrowser.open(authorize_url, new=1, autoraise=True)
-        print('Your browser has been opened to visit:')
-        print()
-        print('    ' + authorize_url)
-        print()
-        print('If your browser is on a different machine then '
-              'exit and re-run this')
-        print('application with the command-line parameter ')
-        print()
-        print('  --noauth_local_webserver')
-        print()
+        print(_BROWSER_OPENED_MESSAGE % authorize_url)
     else:
-        print('Go to the following link in your browser:')
-        print()
-        print('    ' + authorize_url)
-        print()
+        print(_GO_TO_LINK_MESSAGE % authorize_url)
 
     code = None
     if not flags.noauth_local_webserver:
diff --git a/samples/call_compute_service.py b/samples/call_compute_service.py
index c5f372e..72beef0 100644
--- a/samples/call_compute_service.py
+++ b/samples/call_compute_service.py
@@ -5,6 +5,7 @@
 # See:  https://developers.google.com/compute/docs/authentication
 
 from googleapiclient.discovery import build
+
 from oauth2client.client import GoogleCredentials
 
 
diff --git a/samples/googleappengine/call_compute_service_from_gae.py b/samples/googleappengine/call_compute_service_from_gae.py
index b1b1000..3557f58 100644
--- a/samples/googleappengine/call_compute_service_from_gae.py
+++ b/samples/googleappengine/call_compute_service_from_gae.py
@@ -1,8 +1,9 @@
 # To be used to test GoogleCredentials.get_application_default()
 # from devel GAE (ie, dev_appserver.py).
 
-import webapp2
 from googleapiclient.discovery import build
+import webapp2
+
 from oauth2client.client import GoogleCredentials
 
 
@@ -23,4 +24,4 @@ class MainPage(webapp2.RequestHandler):
         self.response.write(get_instances())
 
 
-app = webapp2.WSGIApplication([('/', MainPage),], debug=True)
+app = webapp2.WSGIApplication([('/', MainPage), ], debug=True)
diff --git a/samples/oauth2_for_devices.py b/samples/oauth2_for_devices.py
index 6b3b72e..6e70ff1 100644
--- a/samples/oauth2_for_devices.py
+++ b/samples/oauth2_for_devices.py
@@ -2,10 +2,11 @@
 
 # See:  https://developers.google.com/accounts/docs/OAuth2ForDevices
 
+from googleapiclient.discovery import build
 import httplib2
 from six.moves import input
+
 from oauth2client.client import OAuth2WebServerFlow
-from googleapiclient.discovery import build
 
 CLIENT_ID = "some+client+id"
 CLIENT_SECRET = "some+client+secret"
diff --git a/scripts/run_gce_system_tests.py b/scripts/run_gce_system_tests.py
index 40c105e..d446f9c 100644
--- a/scripts/run_gce_system_tests.py
+++ b/scripts/run_gce_system_tests.py
@@ -13,11 +13,11 @@
 # limitations under the License.
 
 import json
-import unittest2
 
 import httplib2
 from six.moves import http_client
 from six.moves import urllib
+import unittest2
 
 from oauth2client import GOOGLE_TOKEN_INFO_URI
 from oauth2client.client import GoogleCredentials
diff --git a/scripts/run_system_tests.py b/scripts/run_system_tests.py
index f955e3b..535a1ba 100644
--- a/scripts/run_system_tests.py
+++ b/scripts/run_system_tests.py
@@ -17,6 +17,7 @@ import os
 
 import httplib2
 from six.moves import http_client
+
 from oauth2client import client
 from oauth2client.service_account import ServiceAccountCredentials
 
@@ -36,8 +37,8 @@ USER_INFO = 'https://www.googleapis.com/oauth2/v2/userinfo'
 
 def _require_environ():
     if (JSON_KEY_PATH is None or P12_KEY_PATH is None or
-        P12_KEY_EMAIL is None or USER_KEY_PATH is None or
-        USER_KEY_EMAIL is None):
+            P12_KEY_EMAIL is None or USER_KEY_PATH is None or
+            USER_KEY_EMAIL is None):
         raise EnvironmentError('Expected environment variables to be set:',
                                'OAUTH2CLIENT_TEST_JSON_KEY_PATH',
                                'OAUTH2CLIENT_TEST_P12_KEY_PATH',
diff --git a/setup.py b/setup.py
index ef6e2e1..686d1db 100644
--- a/setup.py
+++ b/setup.py
@@ -21,6 +21,11 @@ from __future__ import print_function
 
 import sys
 
+from setuptools import find_packages
+from setuptools import setup
+
+import oauth2client
+
 if sys.version_info < (2, 6):
     print('oauth2client requires python2 version >= 2.6.', file=sys.stderr)
     sys.exit(1)
@@ -28,9 +33,6 @@ if (3, 1) <= sys.version_info < (3, 3):
     print('oauth2client requires python3 version >= 3.3.', file=sys.stderr)
     sys.exit(1)
 
-from setuptools import find_packages
-from setuptools import setup
-
 install_requires = [
     'httplib2>=0.9.1',
     'pyasn1>=0.1.7',
@@ -41,7 +43,6 @@ install_requires = [
 
 long_desc = """The oauth2client is a client library for OAuth 2.0."""
 
-import oauth2client
 version = oauth2client.__version__
 
 setup(
diff --git a/tests/contrib/test_appengine.py b/tests/contrib/test_appengine.py
index de7821c..2290663 100644
--- a/tests/contrib/test_appengine.py
+++ b/tests/contrib/test_appengine.py
@@ -13,21 +13,15 @@
 # limitations under the License.
 
 import datetime
-import httplib2
 import json
 import os
 import tempfile
 import time
-import unittest2
-
-from six.moves import urllib
 
 import dev_appserver
-dev_appserver.fix_sys_path()
-import mock
-import webapp2
 
-from ..http_mock import CacheMock
+dev_appserver.fix_sys_path()
+
 from google.appengine.api import apiproxy_stub
 from google.appengine.api import apiproxy_stub_map
 from google.appengine.api import app_identity
@@ -37,12 +31,25 @@ from google.appengine.api.memcache import memcache_stub
 from google.appengine.ext import db
 from google.appengine.ext import ndb
 from google.appengine.ext import testbed
-from oauth2client.contrib import appengine
-from oauth2client import GOOGLE_TOKEN_URI
+import httplib2
+import mock
+from six.moves import urllib
+import unittest2
+import webapp2
+from webtest import TestApp
+
 from oauth2client import GOOGLE_REVOKE_URI
+from oauth2client import GOOGLE_TOKEN_URI
+from oauth2client.client import _CLOUDSDK_CONFIG_ENV_VAR
+from oauth2client.client import AccessTokenRefreshError
+from oauth2client.client import Credentials
+from oauth2client.client import flow_from_clientsecrets
+from oauth2client.client import OAuth2Credentials
+from oauth2client.client import save_to_well_known_file
 from oauth2client.clientsecrets import _loadfile
-from oauth2client.clientsecrets import TYPE_WEB
 from oauth2client.clientsecrets import InvalidClientSecretsError
+from oauth2client.clientsecrets import TYPE_WEB
+from oauth2client.contrib import appengine
 from oauth2client.contrib.appengine import AppAssertionCredentials
 from oauth2client.contrib.appengine import CredentialsModel
 from oauth2client.contrib.appengine import CredentialsNDBModel
@@ -51,17 +58,10 @@ from oauth2client.contrib.appengine import FlowProperty
 from oauth2client.contrib.appengine import (
     InvalidClientSecretsError as AppEngineInvalidClientSecretsError)
 from oauth2client.contrib.appengine import OAuth2Decorator
-from oauth2client.contrib.appengine import OAuth2DecoratorFromClientSecrets
 from oauth2client.contrib.appengine import oauth2decorator_from_clientsecrets
+from oauth2client.contrib.appengine import OAuth2DecoratorFromClientSecrets
 from oauth2client.contrib.appengine import StorageByKeyName
-from oauth2client.client import _CLOUDSDK_CONFIG_ENV_VAR
-from oauth2client.client import AccessTokenRefreshError
-from oauth2client.client import Credentials
-from oauth2client.client import OAuth2Credentials
-from oauth2client.client import flow_from_clientsecrets
-from oauth2client.client import save_to_well_known_file
-from webtest import TestApp
-
+from ..http_mock import CacheMock
 
 __author__ = 'jcgregorio@google.com (Joe Gregorio)'
 
@@ -847,7 +847,7 @@ class DecoratorTests(unittest2.TestCase):
         # An initial request to an oauth_aware decorated path should
         # not redirect.
         response = self.app.get('/bar_path/2012/01')
-        url = self.decorator.authorize_url()
+        self.decorator.authorize_url()
         response = self.app.get('/oauth2callback', {
             'error': 'Bad<Stuff>Happened\''
         })
@@ -903,9 +903,7 @@ class DecoratorTests(unittest2.TestCase):
 
         with decorator_patch as decorator_mock:
             filename = datafile('client_secrets.json')
-            decorator = oauth2decorator_from_clientsecrets(
-                filename,
-                scope='foo_scope')
+            oauth2decorator_from_clientsecrets(filename, scope='foo_scope')
             decorator_mock.assert_called_once_with(
                 filename,
                 'foo_scope',
@@ -974,7 +972,7 @@ class DecoratorTests(unittest2.TestCase):
     def test_decorator_from_unfilled_client_secrets_required(self):
         MESSAGE = 'File is missing'
         try:
-            decorator = OAuth2DecoratorFromClientSecrets(
+            OAuth2DecoratorFromClientSecrets(
                 datafile('unfilled_client_secrets.json'),
                 scope=['foo_scope', 'bar_scope'], message=MESSAGE)
         except InvalidClientSecretsError:
@@ -983,7 +981,7 @@ class DecoratorTests(unittest2.TestCase):
     def test_decorator_from_unfilled_client_secrets_aware(self):
         MESSAGE = 'File is missing'
         try:
-            decorator = OAuth2DecoratorFromClientSecrets(
+            OAuth2DecoratorFromClientSecrets(
                 datafile('unfilled_client_secrets.json'),
                 scope=['foo_scope', 'bar_scope'], message=MESSAGE)
         except InvalidClientSecretsError:
diff --git a/tests/contrib/test_devshell.py b/tests/contrib/test_devshell.py
index 9fcafd4..4e5ff72 100644
--- a/tests/contrib/test_devshell.py
+++ b/tests/contrib/test_devshell.py
@@ -19,17 +19,17 @@ import json
 import os
 import socket
 import threading
-import unittest2
 
 import mock
+import unittest2
 
-from oauth2client.contrib import devshell
 from oauth2client._helpers import _from_bytes
 from oauth2client._helpers import _to_bytes
 from oauth2client.client import save_to_well_known_file
+from oauth2client.contrib import devshell
 from oauth2client.contrib.devshell import _SendRecv
-from oauth2client.contrib.devshell import CREDENTIAL_INFO_REQUEST_JSON
 from oauth2client.contrib.devshell import CommunicationError
+from oauth2client.contrib.devshell import CREDENTIAL_INFO_REQUEST_JSON
 from oauth2client.contrib.devshell import CredentialInfoResponse
 from oauth2client.contrib.devshell import DEVSHELL_ENV
 from oauth2client.contrib.devshell import DevshellCredentials
diff --git a/tests/contrib/test_django_orm.py b/tests/contrib/test_django_orm.py
index 2924bea..7462e25 100644
--- a/tests/contrib/test_django_orm.py
+++ b/tests/contrib/test_django_orm.py
@@ -19,14 +19,10 @@ Unit tests for objects created from discovery documents.
 
 import base64
 import datetime
-import imp
 import os
 import pickle
-import sys
-import unittest2
-# Mock a Django environment
-from django.conf import global_settings
 
+# Mock a Django environment
 os.environ['DJANGO_SETTINGS_MODULE'] = 'tests.contrib.test_django_settings'
 from django.conf import settings
 
@@ -38,8 +34,6 @@ import django
 django.setup()
 from django.apps import AppConfig
 
-import mock
-
 
 class DjangoOrmTestApp(AppConfig):
     """App Config for Django Helper."""
@@ -48,6 +42,10 @@ class DjangoOrmTestApp(AppConfig):
 
 
 from django.db import models
+import mock
+import unittest2
+
+from oauth2client import GOOGLE_TOKEN_URI
 from oauth2client._helpers import _from_bytes
 from oauth2client.client import Credentials
 from oauth2client.client import Flow
@@ -55,7 +53,6 @@ from oauth2client.client import OAuth2Credentials
 from oauth2client.contrib.django_orm import CredentialsField
 from oauth2client.contrib.django_orm import FlowField
 from oauth2client.contrib.django_orm import Storage
-from oauth2client import GOOGLE_TOKEN_URI
 
 __author__ = 'conleyo@google.com (Conley Owens)'
 
diff --git a/tests/contrib/test_django_util.py b/tests/contrib/test_django_util.py
index 18eab30..11f2dc3 100644
--- a/tests/contrib/test_django_util.py
+++ b/tests/contrib/test_django_util.py
@@ -13,22 +13,23 @@
 # limitations under the License.
 
 import json
-import unittest2
 
-from django.conf.urls import include, url
-from django.core import exceptions
 from django import http
 from django import test
-import mock
-from oauth2client.client import FlowExchangeError, OAuth2WebServerFlow
 import django.conf
+from django.conf.urls import include, url
+from django.core import exceptions
+import mock
+from six.moves import http_client
+from six.moves.urllib import parse
+import unittest2
+
+from oauth2client.client import FlowExchangeError, OAuth2WebServerFlow
 from oauth2client.contrib import django_util
 from oauth2client.contrib.django_util import decorators
 from oauth2client.contrib.django_util import site
 from oauth2client.contrib.django_util import storage
 from oauth2client.contrib.django_util import views
-from six.moves import http_client
-from six.moves.urllib import parse
 
 urlpatterns = [
     url(r'^oauth2/', include(site.urls))
@@ -242,9 +243,8 @@ class Oauth2AuthorizeTest(TestWithSession):
         self.assertTrue(isinstance(response, http.HttpResponseRedirect))
 
     def test_authorize_works_explicit_return_url(self):
-        request = self.factory.get('oauth2/oauth2authorize', data={
-            'return_url':  '/return_endpoint'
-        })
+        request = self.factory.get('oauth2/oauth2authorize',
+                                   data={'return_url': '/return_endpoint'})
         request.session = self.session
         response = views.oauth2_authorize(request)
         self.assertTrue(isinstance(response, http.HttpResponseRedirect))
diff --git a/tests/contrib/test_flask_util.py b/tests/contrib/test_flask_util.py
index f4fe0e9..dbf3cac 100644
--- a/tests/contrib/test_flask_util.py
+++ b/tests/contrib/test_flask_util.py
@@ -15,21 +15,21 @@
 """Unit tests for the Flask utilities"""
 
 import datetime
-import httplib2
 import json
-import unittest2
 
 import flask
-import six.moves.http_client as httplib
+import httplib2
 import mock
+import six.moves.http_client as httplib
 import six.moves.urllib.parse as urlparse
+import unittest2
 
+from oauth2client import clientsecrets
 from oauth2client import GOOGLE_AUTH_URI
 from oauth2client import GOOGLE_TOKEN_URI
-from oauth2client import clientsecrets
+from oauth2client.client import OAuth2Credentials
 from oauth2client.contrib.flask_util import _get_flow_for_token
 from oauth2client.contrib.flask_util import UserOAuth2 as FlaskOAuth2
-from oauth2client.client import OAuth2Credentials
 
 
 __author__ = 'jonwayne@google.com (Jon Wayne Parrott)'
@@ -474,7 +474,8 @@ class FlaskOAuth2Tests(unittest2.TestCase):
             # Starting the authorization flow should include the
             # include_granted_scopes parameter as well as the scopes.
             response = client.get(response.headers['Location'][17:])
-            q = urlparse.parse_qs(response.headers['Location'].split('?', 1)[1])
+            q = urlparse.parse_qs(
+                response.headers['Location'].split('?', 1)[1])
             self.assertIn('include_granted_scopes', q)
             self.assertEqual(
                 set(q['scope'][0].split(' ')),
diff --git a/tests/contrib/test_gce.py b/tests/contrib/test_gce.py
index 1974020..36ea83f 100644
--- a/tests/contrib/test_gce.py
+++ b/tests/contrib/test_gce.py
@@ -15,18 +15,18 @@
 """Unit tests for oauth2client.contrib.gce."""
 
 import datetime
-import httplib2
 import json
 
+import httplib2
 import mock
 from six.moves import http_client
+from tests.contrib.test_metadata import request_mock
 import unittest2
 
-from oauth2client.client import save_to_well_known_file
 from oauth2client.client import HttpAccessTokenRefreshError
+from oauth2client.client import save_to_well_known_file
 from oauth2client.contrib.gce import _SCOPES_WARNING
 from oauth2client.contrib.gce import AppAssertionCredentials
-from tests.contrib.test_metadata import request_mock
 
 __author__ = 'jcgregorio@google.com (Joe Gregorio)'
 
@@ -36,6 +36,7 @@ SERVICE_ACCOUNT_INFO = {
     'aliases': ['default']
 }
 
+
 class AppAssertionCredentialsTests(unittest2.TestCase):
 
     def test_constructor(self):
@@ -78,11 +79,13 @@ class AppAssertionCredentialsTests(unittest2.TestCase):
         credentials.get_access_token(http=http_mock)
         self.assertEqual(credentials.access_token, 'A')
         self.assertTrue(credentials.access_token_expired)
-        get_token.assert_called_with(http_request, service_account='a@example.com')
+        get_token.assert_called_with(http_request,
+                                     service_account='a@example.com')
         credentials.get_access_token(http=http_mock)
         self.assertEqual(credentials.access_token, 'B')
         self.assertFalse(credentials.access_token_expired)
-        get_token.assert_called_with(http_request, service_account='a@example.com')
+        get_token.assert_called_with(http_request,
+                                     service_account='a@example.com')
         get_info.assert_not_called()
 
     def test_refresh_token_failed_fetch(self):
@@ -124,7 +127,8 @@ class AppAssertionCredentialsTests(unittest2.TestCase):
         self.assertFalse(credentials.invalid)
         credentials.retrieve_scopes(http_mock)
         # Assert scopes weren't refetched
-        metadata.assert_called_once_with(http_request, service_account='default')
+        metadata.assert_called_once_with(http_request,
+                                         service_account='default')
 
     @mock.patch('oauth2client.contrib._metadata.get_service_account_info',
                 side_effect=httplib2.HttpLib2Error('No Such Email'))
@@ -135,7 +139,8 @@ class AppAssertionCredentialsTests(unittest2.TestCase):
         with self.assertRaises(httplib2.HttpLib2Error):
             credentials.retrieve_scopes(http_mock)
 
-        metadata.assert_called_once_with(http_request, service_account='b@example.com')
+        metadata.assert_called_once_with(http_request,
+                                         service_account='b@example.com')
 
     def test_save_to_well_known_file(self):
         import os
diff --git a/tests/contrib/test_keyring_storage.py b/tests/contrib/test_keyring_storage.py
index 3ebf48b..d3a032a 100644
--- a/tests/contrib/test_keyring_storage.py
+++ b/tests/contrib/test_keyring_storage.py
@@ -15,11 +15,11 @@
 """Tests for oauth2client.contrib.keyring_storage."""
 
 import datetime
-import keyring
 import threading
-import unittest2
 
+import keyring
 import mock
+import unittest2
 
 from oauth2client import GOOGLE_TOKEN_URI
 from oauth2client.client import OAuth2Credentials
diff --git a/tests/contrib/test_metadata.py b/tests/contrib/test_metadata.py
index 8c6b973..3fe3338 100644
--- a/tests/contrib/test_metadata.py
+++ b/tests/contrib/test_metadata.py
@@ -13,12 +13,12 @@
 # limitations under the License.
 
 import datetime
-import httplib2
 import json
-import mock
-import unittest2
 
+import httplib2
+import mock
 from six.moves import http_client
+import unittest2
 
 from oauth2client.contrib import _metadata
 
@@ -81,7 +81,7 @@ class TestMetadata(unittest2.TestCase):
         self.assertEqual(
             expiry, datetime.datetime.min + datetime.timedelta(seconds=100))
         http_request.assert_called_once_with(
-            EXPECTED_URL+'/token',
+            EXPECTED_URL + '/token',
             **EXPECTED_KWARGS
         )
         now.assert_called_once_with()
@@ -92,6 +92,6 @@ class TestMetadata(unittest2.TestCase):
         info = _metadata.get_service_account_info(http_request)
         self.assertEqual(info, DATA)
         http_request.assert_called_once_with(
-            EXPECTED_URL+'/?recursive=True',
+            EXPECTED_URL + '/?recursive=True',
             **EXPECTED_KWARGS
         )
diff --git a/tests/contrib/test_multistore_file.py b/tests/contrib/test_multistore_file.py
index de54cb0..469743b 100644
--- a/tests/contrib/test_multistore_file.py
+++ b/tests/contrib/test_multistore_file.py
@@ -19,9 +19,9 @@ import errno
 import os
 import stat
 import tempfile
-import unittest2
 
 import mock
+import unittest2
 
 from oauth2client import util
 from oauth2client.client import OAuth2Credentials
diff --git a/tests/contrib/test_sqlalchemy.py b/tests/contrib/test_sqlalchemy.py
index 8f671a3..14067e0 100644
--- a/tests/contrib/test_sqlalchemy.py
+++ b/tests/contrib/test_sqlalchemy.py
@@ -14,14 +14,15 @@
 
 import datetime
 
-import oauth2client
-import oauth2client.client
-import oauth2client.contrib.sqlalchemy
 import sqlalchemy
 import sqlalchemy.ext.declarative
 import sqlalchemy.orm
 import unittest2
 
+import oauth2client
+import oauth2client.client
+import oauth2client.contrib.sqlalchemy
+
 Base = sqlalchemy.ext.declarative.declarative_base()
 
 
diff --git a/tests/contrib/test_xsrfutil.py b/tests/contrib/test_xsrfutil.py
index 363a189..d6eddd6 100644
--- a/tests/contrib/test_xsrfutil.py
+++ b/tests/contrib/test_xsrfutil.py
@@ -15,9 +15,9 @@
 """Tests for oauth2client.contrib.xsrfutil."""
 
 import base64
-import unittest2
 
 import mock
+import unittest2
 
 from oauth2client._helpers import _to_bytes
 from oauth2client.contrib import xsrfutil
@@ -49,7 +49,6 @@ class Test_generate_token(unittest2.TestCase):
 
     def test_it(self):
         digest = b'foobar'
-        curr_time = 1440449755.74
         digester = mock.MagicMock()
         digester.digest = mock.MagicMock(name='digest', return_value=digest)
         with mock.patch('oauth2client.contrib.xsrfutil.hmac') as hmac:
diff --git a/tests/test__pure_python_crypt.py b/tests/test__pure_python_crypt.py
index 754b29d..bae2bcd 100644
--- a/tests/test__pure_python_crypt.py
+++ b/tests/test__pure_python_crypt.py
@@ -22,8 +22,8 @@ import rsa
 import six
 import unittest2
 
-from oauth2client._helpers import _from_bytes
 from oauth2client import _pure_python_crypt
+from oauth2client._helpers import _from_bytes
 from oauth2client.crypt import RsaSigner
 from oauth2client.crypt import RsaVerifier
 
@@ -33,7 +33,7 @@ class TestRsaVerifier(unittest2.TestCase):
     PUBLIC_KEY_FILENAME = os.path.join(os.path.dirname(__file__),
                                        'data', 'privatekey.pub')
     PUBLIC_CERT_FILENAME = os.path.join(os.path.dirname(__file__),
-                                       'data', 'public_cert.pem')
+                                        'data', 'public_cert.pem')
     PRIVATE_KEY_FILENAME = os.path.join(os.path.dirname(__file__),
                                         'data', 'privatekey.pem')
 
diff --git a/tests/test__pycrypto_crypt.py b/tests/test__pycrypto_crypt.py
index 99e968a..53c7f07 100644
--- a/tests/test__pycrypto_crypt.py
+++ b/tests/test__pycrypto_crypt.py
@@ -14,6 +14,7 @@
 """Unit tests for oauth2client._pycrypto_crypt."""
 
 import os
+
 import unittest2
 
 from oauth2client.crypt import PyCryptoSigner
diff --git a/tests/test_client.py b/tests/test_client.py
index 8099538..d57dacf 100644
--- a/tests/test_client.py
+++ b/tests/test_client.py
@@ -34,38 +34,12 @@ from six.moves import http_client
 from six.moves import urllib
 import unittest2
 
-from .http_mock import CacheMock
-from .http_mock import HttpMock
-from .http_mock import HttpMockSequence
-from oauth2client import GOOGLE_REVOKE_URI
-from oauth2client import GOOGLE_TOKEN_URI
-from oauth2client import GOOGLE_TOKEN_INFO_URI
 from oauth2client import client
+from oauth2client import GOOGLE_REVOKE_URI
+from oauth2client import GOOGLE_TOKEN_INFO_URI
+from oauth2client import GOOGLE_TOKEN_URI
 from oauth2client import util as oauth2client_util
-from oauth2client.client import AccessTokenCredentials
-from oauth2client.client import AccessTokenCredentialsError
-from oauth2client.client import HttpAccessTokenRefreshError
-from oauth2client.client import ADC_HELP_MSG
-from oauth2client.client import AssertionCredentials
-from oauth2client.client import AUTHORIZED_USER
-from oauth2client.client import Credentials
-from oauth2client.client import DEFAULT_ENV_NAME
-from oauth2client.client import DeviceFlowInfo
-from oauth2client.client import Error
-from oauth2client.client import ApplicationDefaultCredentialsError
-from oauth2client.client import FlowExchangeError
-from oauth2client.client import GoogleCredentials
-from oauth2client.client import GOOGLE_APPLICATION_CREDENTIALS
-from oauth2client.client import MemoryCache
-from oauth2client.client import NonAsciiHeaderError
-from oauth2client.client import OAuth2Credentials
-from oauth2client.client import OAuth2WebServerFlow
-from oauth2client.client import OOB_CALLBACK_URN
-from oauth2client.client import REFRESH_STATUS_CODES
-from oauth2client.client import SERVICE_ACCOUNT
-from oauth2client.client import Storage
-from oauth2client.client import TokenRevokeError
-from oauth2client.client import VerifyJwtTokenError
+from oauth2client._helpers import _to_bytes
 from oauth2client.client import _extract_id_token
 from oauth2client.client import _get_application_default_credential_from_file
 from oauth2client.client import _get_environment_variable_file
@@ -76,15 +50,41 @@ from oauth2client.client import _raise_exception_for_missing_fields
 from oauth2client.client import _raise_exception_for_reading_json
 from oauth2client.client import _update_query_params
 from oauth2client.client import _WELL_KNOWN_CREDENTIALS_FILE
+from oauth2client.client import AccessTokenCredentials
+from oauth2client.client import AccessTokenCredentialsError
+from oauth2client.client import ADC_HELP_MSG
+from oauth2client.client import ApplicationDefaultCredentialsError
+from oauth2client.client import AssertionCredentials
+from oauth2client.client import AUTHORIZED_USER
+from oauth2client.client import Credentials
 from oauth2client.client import credentials_from_clientsecrets_and_code
 from oauth2client.client import credentials_from_code
+from oauth2client.client import DEFAULT_ENV_NAME
+from oauth2client.client import DeviceFlowInfo
+from oauth2client.client import Error
 from oauth2client.client import flow_from_clientsecrets
+from oauth2client.client import FlowExchangeError
+from oauth2client.client import GOOGLE_APPLICATION_CREDENTIALS
+from oauth2client.client import GoogleCredentials
+from oauth2client.client import HttpAccessTokenRefreshError
+from oauth2client.client import MemoryCache
+from oauth2client.client import NonAsciiHeaderError
+from oauth2client.client import OAuth2Credentials
+from oauth2client.client import OAuth2WebServerFlow
+from oauth2client.client import OOB_CALLBACK_URN
+from oauth2client.client import REFRESH_STATUS_CODES
 from oauth2client.client import save_to_well_known_file
+from oauth2client.client import SERVICE_ACCOUNT
+from oauth2client.client import Storage
+from oauth2client.client import TokenRevokeError
+from oauth2client.client import VerifyJwtTokenError
 from oauth2client.clientsecrets import _loadfile
 from oauth2client.clientsecrets import InvalidClientSecretsError
 from oauth2client.clientsecrets import TYPE_WEB
 from oauth2client.service_account import ServiceAccountCredentials
-from oauth2client._helpers import _to_bytes
+from .http_mock import CacheMock
+from .http_mock import HttpMock
+from .http_mock import HttpMockSequence
 
 __author__ = 'jcgregorio@google.com (Joe Gregorio)'
 
@@ -124,7 +124,7 @@ class CredentialsTests(unittest2.TestCase):
     def test_to_from_json(self):
         credentials = Credentials()
         json = credentials.to_json()
-        restored = Credentials.new_from_json(json)
+        Credentials.new_from_json(json)
 
     def test_authorize_abstract(self):
         credentials = Credentials()
@@ -457,7 +457,7 @@ class GoogleCredentialsTests(unittest2.TestCase):
                             client._METADATA_FLAVOR_HEADER)
                 else:
                     self.assertEqual(
-                            http_client_module.HTTPConnection.mock_calls, [])
+                        http_client_module.HTTPConnection.mock_calls, [])
                     self.assertEqual(connection.getresponse.mock_calls, [])
                     # Remaining calls are not "getresponse"
                     self.assertEqual(connection.method_calls, [])
@@ -1863,8 +1863,7 @@ class OAuth2WebServerFlowTest(unittest2.TestCase):
         ])
 
         with self.assertRaises(FlowExchangeError):
-            credentials = self.flow.step2_exchange(code='some random code',
-                                                   http=http)
+            self.flow.step2_exchange(code='some random code', http=http)
 
     def test_urlencoded_exchange_failure(self):
         http = HttpMockSequence([
@@ -1873,8 +1872,7 @@ class OAuth2WebServerFlowTest(unittest2.TestCase):
 
         with self.assertRaisesRegexp(FlowExchangeError,
                                      'invalid_request'):
-            credentials = self.flow.step2_exchange(code='some random code',
-                                                   http=http)
+            self.flow.step2_exchange(code='some random code', http=http)
 
     def test_exchange_failure_with_json_error(self):
         # Some providers have 'error' attribute as a JSON object
@@ -1890,8 +1888,7 @@ class OAuth2WebServerFlowTest(unittest2.TestCase):
         http = HttpMockSequence([({'status': '400'}, payload)])
 
         with self.assertRaises(FlowExchangeError):
-            credentials = self.flow.step2_exchange(code='some random code',
-                                                   http=http)
+            self.flow.step2_exchange(code='some random code', http=http)
 
     def _exchange_success_test_helper(self, code=None, device_flow_info=None):
         payload = (b'{'
@@ -2040,9 +2037,8 @@ class OAuth2WebServerFlowTest(unittest2.TestCase):
         http = HttpMockSequence([({'status': '200'}, payload)])
 
         code = {'error': 'thou shall not pass'}
-        with self.assertRaisesRegexp(FlowExchangeError,
-                                     'shall not pass'):
-            credentials = self.flow.step2_exchange(code=code, http=http)
+        with self.assertRaisesRegexp(FlowExchangeError, 'shall not pass'):
+            self.flow.step2_exchange(code=code, http=http)
 
     def test_exchange_id_token_fail(self):
         payload = (b'{'
@@ -2153,7 +2149,8 @@ class FlowFromCachedClientsecrets(unittest2.TestCase):
         filename = object()
         cache = object()
         message = 'hi mom'
-        expected = 'The client secrets were invalid: \n{0}\n{1}'.format('foobar', 'hi mom')
+        expected = ('The client secrets were invalid: '
+                    '\n{0}\n{1}'.format('foobar', 'hi mom'))
 
         flow_from_clientsecrets(filename, None, cache=cache, message=message)
         sys_exit.assert_called_once_with(expected)
@@ -2190,9 +2187,8 @@ class CredentialsFromCodeTests(unittest2.TestCase):
             ({'status': '200'}, payload.encode('utf-8')),
         ])
         credentials = credentials_from_code(self.client_id, self.client_secret,
-                                            self.scope, self.code,
-                                            redirect_uri=self.redirect_uri,
-                                            http=http)
+                                            self.scope, self.code, http=http,
+                                            redirect_uri=self.redirect_uri)
         self.assertEqual(credentials.access_token, token)
         self.assertNotEqual(None, credentials.token_expiry)
         self.assertEqual(set(['foo']), credentials.scopes)
@@ -2203,11 +2199,9 @@ class CredentialsFromCodeTests(unittest2.TestCase):
         ])
 
         with self.assertRaises(FlowExchangeError):
-            credentials = credentials_from_code(self.client_id,
-                                                self.client_secret,
-                                                self.scope, self.code,
-                                                redirect_uri=self.redirect_uri,
-                                                http=http)
+            credentials_from_code(self.client_id, self.client_secret,
+                                  self.scope, self.code, http=http,
+                                  redirect_uri=self.redirect_uri)
 
     def test_exchange_code_and_file_for_token(self):
         payload = (b'{'
@@ -2241,7 +2235,7 @@ class CredentialsFromCodeTests(unittest2.TestCase):
         ])
 
         with self.assertRaises(FlowExchangeError):
-            credentials = credentials_from_clientsecrets_and_code(
+            credentials_from_clientsecrets_and_code(
                 datafile('client_secrets.json'), self.scope,
                 self.code, http=http)
 
diff --git a/tests/test_clientsecrets.py b/tests/test_clientsecrets.py
index 5065e31..95be076 100644
--- a/tests/test_clientsecrets.py
+++ b/tests/test_clientsecrets.py
@@ -18,13 +18,14 @@ import errno
 from io import StringIO
 import os
 import tempfile
+
 import unittest2
 
-from oauth2client._helpers import _from_bytes
+from oauth2client import clientsecrets
 from oauth2client import GOOGLE_AUTH_URI
 from oauth2client import GOOGLE_REVOKE_URI
 from oauth2client import GOOGLE_TOKEN_URI
-from oauth2client import clientsecrets
+from oauth2client._helpers import _from_bytes
 
 
 __author__ = 'jcgregorio@google.com (Joe Gregorio)'
@@ -121,11 +122,11 @@ class Test__validate_clientsecrets(unittest2.TestCase):
 
     def test_success_type_web(self):
         client_info = {
-                'client_id': 'eye-dee',
-                'client_secret': 'seekrit',
-                'redirect_uris': None,
-                'auth_uri': None,
-                'token_uri': None,
+            'client_id': 'eye-dee',
+            'client_secret': 'seekrit',
+            'redirect_uris': None,
+            'auth_uri': None,
+            'token_uri': None,
         }
         clientsecrets_dict = {
             clientsecrets.TYPE_WEB: client_info,
@@ -135,11 +136,11 @@ class Test__validate_clientsecrets(unittest2.TestCase):
 
     def test_success_type_installed(self):
         client_info = {
-                'client_id': 'eye-dee',
-                'client_secret': 'seekrit',
-                'redirect_uris': None,
-                'auth_uri': None,
-                'token_uri': None,
+            'client_id': 'eye-dee',
+            'client_secret': 'seekrit',
+            'redirect_uris': None,
+            'auth_uri': None,
+            'token_uri': None,
         }
         clientsecrets_dict = {
             clientsecrets.TYPE_INSTALLED: client_info,
diff --git a/tests/test_crypt.py b/tests/test_crypt.py
index 55e60d9..d7312ef 100644
--- a/tests/test_crypt.py
+++ b/tests/test_crypt.py
@@ -14,13 +14,13 @@
 
 import base64
 import os
-import unittest2
 
 import mock
+import unittest2
 
 from oauth2client import _helpers
-from oauth2client.client import HAS_OPENSSL
 from oauth2client import crypt
+from oauth2client.client import HAS_OPENSSL
 from oauth2client.service_account import ServiceAccountCredentials
 
 
@@ -48,7 +48,7 @@ class Test_pkcs12_key_as_pem(unittest2.TestCase):
             'some_account@example.com',
             filename,
             scopes='read+write')
-        credentials._kwargs['sub'] ='joe@example.org'
+        credentials._kwargs['sub'] = 'joe@example.org'
         return credentials
 
     def _succeeds_helper(self, password=None):
@@ -171,6 +171,7 @@ class Test__check_audience(unittest2.TestCase):
         with self.assertRaises(crypt.AppIdentityError):
             crypt._check_audience(payload_dict, audience2)
 
+
 class Test__verify_time_range(unittest2.TestCase):
 
     def _exception_helper(self, payload_dict):
diff --git a/tests/test_file.py b/tests/test_file.py
index 27f3cab..6962dee 100644
--- a/tests/test_file.py
+++ b/tests/test_file.py
@@ -24,15 +24,16 @@ import os
 import pickle
 import stat
 import tempfile
-import unittest2
 
-from .http_mock import HttpMockSequence
 import six
+from six.moves import http_client
+import unittest2
 
 from oauth2client import file
 from oauth2client.client import AccessTokenCredentials
 from oauth2client.client import OAuth2Credentials
-from six.moves import http_client
+from .http_mock import HttpMockSequence
+
 try:
     # Python2
     from future_builtins import oct
diff --git a/tests/test_jwt.py b/tests/test_jwt.py
index f567f5d..bbcdd3c 100644
--- a/tests/test_jwt.py
+++ b/tests/test_jwt.py
@@ -21,16 +21,16 @@ import time
 import mock
 import unittest2
 
-from .http_mock import HttpMockSequence
-from oauth2client.client import Credentials
-from oauth2client.client import VerifyJwtTokenError
-from oauth2client.client import verify_id_token
-from oauth2client.client import HAS_OPENSSL
-from oauth2client.client import HAS_CRYPTO
 from oauth2client import crypt
+from oauth2client.client import Credentials
+from oauth2client.client import HAS_CRYPTO
+from oauth2client.client import HAS_OPENSSL
+from oauth2client.client import verify_id_token
+from oauth2client.client import VerifyJwtTokenError
 from oauth2client.file import Storage
 from oauth2client.service_account import _PASSWORD_DEFAULT
 from oauth2client.service_account import ServiceAccountCredentials
+from .http_mock import HttpMockSequence
 
 
 __author__ = 'jcgregorio@google.com (Joe Gregorio)'
@@ -147,15 +147,14 @@ class CryptTests(unittest2.TestCase):
 
     def test_verify_id_token_with_certs_uri_fails(self):
         jwt = self._create_signed_jwt()
+        test_email = 'some_audience_address@testing.gserviceaccount.com'
 
         http = HttpMockSequence([
             ({'status': '404'}, datafile('certs.json')),
         ])
 
         with self.assertRaises(VerifyJwtTokenError):
-            verify_id_token(jwt,
-                            'some_audience_address@testing.gserviceaccount.com',
-                            http=http)
+            verify_id_token(jwt, test_email, http=http)
 
     def test_verify_id_token_bad_tokens(self):
         private_key = datafile('privatekey.' + self.format_)
diff --git a/tests/test_service_account.py b/tests/test_service_account.py
index 9c7f444..7bca56b 100644
--- a/tests/test_service_account.py
+++ b/tests/test_service_account.py
@@ -20,20 +20,19 @@ Unit tests for service account credentials implemented using RSA.
 import datetime
 import json
 import os
-import rsa
 import tempfile
 
 import httplib2
 import mock
+import rsa
+from six import BytesIO
 import unittest2
 
-from .http_mock import HttpMockSequence
 from oauth2client import crypt
 from oauth2client.service_account import _JWTAccessCredentials
-from oauth2client.service_account import ServiceAccountCredentials
 from oauth2client.service_account import SERVICE_ACCOUNT
-
-from six import BytesIO
+from oauth2client.service_account import ServiceAccountCredentials
+from .http_mock import HttpMockSequence
 
 
 def data_filename(filename):
@@ -114,7 +113,7 @@ class ServiceAccountCredentialsTests(unittest2.TestCase):
                 return_value=object())
     def test_from_json_keyfile_name_factory(self, signer_factory):
         client_id = 'id123'
-        client_email= 'foo@bar.com'
+        client_email = 'foo@bar.com'
         private_key_id = 'pkid456'
         private_key = 's3kr3tz'
         payload = {
@@ -179,12 +178,14 @@ class ServiceAccountCredentialsTests(unittest2.TestCase):
         for creds in (creds_from_filename, creds_from_file_contents):
             self.assertIsInstance(creds, ServiceAccountCredentials)
             self.assertIsNone(creds.client_id)
-            self.assertEqual(creds._service_account_email, service_account_email)
+            self.assertEqual(creds._service_account_email,
+                             service_account_email)
             self.assertIsNone(creds._private_key_id)
             self.assertIsNone(creds._private_key_pkcs8_pem)
             self.assertEqual(creds._private_key_pkcs12, key_contents)
             if private_key_password is not None:
-                self.assertEqual(creds._private_key_password, private_key_password)
+                self.assertEqual(creds._private_key_password,
+                                 private_key_password)
             self.assertEqual(creds._scopes, ' '.join(scopes))
             self.assertEqual(creds.token_uri, token_uri)
             self.assertEqual(creds.revoke_uri, revoke_uri)
@@ -435,13 +436,13 @@ class JWTAccessCredentialsTests(unittest2.TestCase):
         utcnow.return_value = T1_DATE
         time.return_value = T1
 
-        token_info = self.jwt.get_access_token(additional_claims=
-                                               {'aud': 'https://test2.url.com',
-                                                'sub': 'dummy2@google.com'
-                                               })
+        token_info = self.jwt.get_access_token(
+            additional_claims={'aud': 'https://test2.url.com',
+                               'sub': 'dummy2@google.com'
+                               })
         payload = crypt.verify_signed_jwt_with_certs(
             token_info.access_token,
-            {'key' : datafile('public_cert.pem')}, 
+            {'key': datafile('public_cert.pem')},
             audience='https://test2.url.com')
         expires_in = token_info.expires_in
         self.assertEqual(payload['iss'], self.service_account_email)
@@ -449,13 +450,13 @@ class JWTAccessCredentialsTests(unittest2.TestCase):
         self.assertEqual(payload['iat'], T1)
         self.assertEqual(payload['exp'], T1_EXPIRY)
         self.assertEqual(expires_in, T1_EXPIRY - T1)
- 
+
     def test_revoke(self):
         self.jwt.revoke(None)
-     
+
     def test_create_scoped_required(self):
         self.assertTrue(self.jwt.create_scoped_required())
-    
+
     def test_create_scoped(self):
         self.jwt._private_key_pkcs12 = ''
         self.jwt._private_key_password = ''
@@ -464,7 +465,7 @@ class JWTAccessCredentialsTests(unittest2.TestCase):
         self.assertNotEqual(self.jwt, new_credentials)
         self.assertIsInstance(new_credentials, ServiceAccountCredentials)
         self.assertEqual('dummy_scope', new_credentials._scopes)
-    
+
     @mock.patch('oauth2client.service_account._UTCNOW')
     @mock.patch('oauth2client.client._UTCNOW')
     @mock.patch('time.time')
@@ -479,7 +480,7 @@ class JWTAccessCredentialsTests(unittest2.TestCase):
             bearer, token = headers[b'Authorization'].split()
             payload = crypt.verify_signed_jwt_with_certs(
                 token,
-                {'key': datafile('public_cert.pem')}, 
+                {'key': datafile('public_cert.pem')},
                 audience=self.url)
             self.assertEqual(payload['iss'], self.service_account_email)
             self.assertEqual(payload['sub'], self.service_account_email)
diff --git a/tests/test_tools.py b/tests/test_tools.py
index 8efe9e1..69c28ca 100644
--- a/tests/test_tools.py
+++ b/tests/test_tools.py
@@ -20,9 +20,9 @@ import mock
 from six.moves.urllib import request
 import unittest2
 
+from oauth2client import tools
 from oauth2client.client import FlowExchangeError
 from oauth2client.client import OOB_CALLBACK_URN
-from oauth2client import tools
 
 try:
     import argparse
@@ -68,11 +68,10 @@ class TestRunFlow(unittest2.TestCase):
         self.server_flags = argparse.Namespace(
             noauth_local_webserver=False,
             logging_level='INFO',
-            auth_host_port=[8080,],
+            auth_host_port=[8080, ],
             auth_host_name='localhost')
 
-    @mock.patch.object(sys, 'argv',
-        ['ignored', '--noauth_local_webserver'])
+    @mock.patch.object(sys, 'argv', ['ignored', '--noauth_local_webserver'])
     @mock.patch('oauth2client.tools.logging')
     @mock.patch('oauth2client.tools.input')
     def test_run_flow_no_webserver(self, input_mock, logging_mock):
@@ -149,8 +148,7 @@ class TestRunFlow(unittest2.TestCase):
 
         # Exchange returned an error code.
         with self.assertRaises(SystemExit):
-            returned_credentials = tools.run_flow(
-                self.flow, self.storage, flags=self.server_flags)
+            tools.run_flow(self.flow, self.storage, flags=self.server_flags)
 
         self.assertTrue(self.server.handle_request.called)
 
@@ -164,8 +162,7 @@ class TestRunFlow(unittest2.TestCase):
 
         # No code found in response
         with self.assertRaises(SystemExit):
-            returned_credentials = tools.run_flow(
-                self.flow, self.storage, flags=self.server_flags)
+            tools.run_flow(self.flow, self.storage, flags=self.server_flags)
 
         self.assertTrue(self.server.handle_request.called)
 
diff --git a/tests/test_util.py b/tests/test_util.py
index 9f1d7ed..533460f 100644
--- a/tests/test_util.py
+++ b/tests/test_util.py
@@ -9,7 +9,6 @@ from oauth2client import util
 __author__ = 'jcgregorio@google.com (Joe Gregorio)'
 
 
-
 class PositionalTests(unittest2.TestCase):
 
     def test_usage(self):
@@ -45,7 +44,6 @@ class PositionalTests(unittest2.TestCase):
         with self.assertRaises(TypeError):
             fn3(1, 2)
 
-
     @mock.patch('oauth2client.util.logger')
     def test_enforcement_warning(self, mock_logger):
         util.positional_parameters_enforcement = util.POSITIONAL_WARNING
@@ -57,7 +55,6 @@ class PositionalTests(unittest2.TestCase):
         self.assertTrue(fn(1, 2))
         self.assertTrue(mock_logger.warning.called)
 
-
     @mock.patch('oauth2client.util.logger')
     def test_enforcement_ignore(self, mock_logger):
         util.positional_parameters_enforcement = util.POSITIONAL_IGNORE
@@ -104,7 +101,6 @@ class StringToScopeTests(unittest2.TestCase):
             self.assertEqual(expected, util.string_to_scopes(case))
 
 
-
 class AddQueryParameterTests(unittest2.TestCase):
 
     def test__add_query_parameter(self):
diff --git a/tox.ini b/tox.ini
index eba723c..1c9d92b 100644
--- a/tox.ini
+++ b/tox.ini
@@ -154,3 +154,24 @@ commands =
 deps =
     pycrypto>=2.6
 passenv = {[testenv:system-tests]passenv}
+
+[testenv:flake8]
+commands = flake8 --import-order-style google {posargs}
+deps =
+    flake8-putty
+    flake8-import-order
+
+[flake8]
+exclude = .tox,.git,./*.egg,build,
+application-import-names = oauth2client
+putty-ignore =
+  # E402 module level import not at top of file
+  # These files have needed configurations defined before import
+  docs/conf.py : E402
+  tests/contrib/test_appengine.py : E402
+  # Additionally, ignore E100 (imports in wrong order) for Django configuration
+  tests/contrib/test_django_orm.py : E402,I100
+  # E501 line too long
+  # Ignore lines over 80 chars that include "http:" or "https:"
+  /http:/ : E501
+  /https:/ : E501