[Findit] Extending versioned_model.py to support versioning multiple entities of the same class.

appengine/findit/model/versioned_config.py

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Versioned singleton entity with the global configuration."""
 
 import logging
 
 from google.appengine.ext import ndb
 
 from model.versioned_model import VersionedModel
 
 
 class VersionedConfig(VersionedModel):
   """Singleton entity with the global configuration of the service.
 
   All changes are stored in the revision log.
   """
 
   # When this revision of configuration was created.
   updated_ts = ndb.DateTimeProperty(indexed=False, auto_now=True)
 
   # Who created this revision of configuration.
   updated_by = ndb.StringProperty(indexed=False)
 
   @classmethod
   def Get(cls, version=None):
     """Returns the version of the config entity, the latest if not specified."""
-    config_data = cls.GetVersion(version)
+    config_data = cls.GetVersion(version=version)
     return config_data or cls() if version is None else config_data
 
   def Update(self, user, is_admin, **kwargs):
     """Applies |kwargs| dict to the entity and stores the entity if changed."""
     if not is_admin:
       raise Exception('Only admin could update config.')
 
     dirty = False
     for k, v in kwargs.iteritems():
       assert k in self._properties, k
       if getattr(self, k) != v:
         setattr(self, k, v)
         dirty = True
 
     if dirty:
       user_name = user.email().split('@')[0]
       self.updated_by = user_name
       self.Save()
       logging.info('Config %s was updated by %s', self.__class__, user_name)
 
     return dirty