Fix toplevel import of validate() (Closes #2).

README

@@ -113,6 +113,17 @@ Obviously, :class:`Versions <Version>` can be compared:
     False
 
 
+It is also possible to check whether a given string is a proper semantic version string:
+
+
+.. code-block:: pycon
+
+    >>> semantic_version.validate('0.1.3')
+    True
+    >>> semantic_version.validate('0a2')
+    False
+
+
 Requirement specification
 -------------------------
 
@@ -224,6 +235,7 @@ definition or (for the empty pre-release number) if a single dash is appended
     >>> Version('0.1.0-alpha') in Spec('>=0.1.0-')  # Include pre-release in checks
     False
 
+
 Including build identifiers in specifications
 """""""""""""""""""""""""""""""""""""""""""""
 

src/semantic_version/__init__.py

@@ -7,4 +7,4 @@ __author__ = "Raphaël Barrois <raphael.barrois+semver@polytechnique.org>"
 __version__ = '2.2.0'
 
 
-from .base import compare, match, Spec, SpecItem, Version
+from .base import compare, match, validate, Spec, SpecItem, Version