code: def locked_get(self):
          
          serialized = self._dictionary.get(self._key)
  
          if serialized is None:
              return None
  
          credentials = client.OAuth2Credentials.from_json(serialized)
          credentials.set_store(self)
  
          return credentials
docs: Retrieve the credentials from the dictionary, if they exist.
  
          Returns: A :class:`oauth2client.client.OAuth2Credentials` instance.