diff --git a/setup.py b/setup.py
index d191c85..fdd978d 100644
--- a/setup.py
+++ b/setup.py
@@ -1,6 +1,6 @@
 from setuptools import setup
 
-VERSION = "0.8.0"
+VERSION = "0.9.0"
 
 
 setup(
@@ -12,7 +12,7 @@ setup(
     author_email="liris.pp@gmail.com",
     license="LGPL",
     url="https://github.com/liris/websocket-client",
-    classifiers = [
+    classifiers=[
         "Development Status :: 3 - Alpha",
         "License :: OSI Approved :: GNU Library or Lesser General Public License (LGPL)",
         "Programming Language :: Python",
diff --git a/websocket.py b/websocket.py
index 1869d26..377eb42 100644
--- a/websocket.py
+++ b/websocket.py
@@ -700,7 +700,9 @@ class WebSocketApp(object):
 
     def send(self, data, opcode = ABNF.OPCODE_TEXT):
         """
-        send message. data must be utf-8 string or unicode.
+        send message. 
+        data: message to send. If you set opcode to OPCODE_TEXT, data must be utf-8 string or unicode.
+        opcode: operation code of data. default is OPCODE_TEXT.
         """
         if self.sock.send(data, opcode) == 0:
             raise WebSocketConnectionClosedException()