def _use_datastore(self, key, options=None):
flag = ContextOptions.use_datastore(options)<EOL>if flag is None:<EOL><INDENT>flag = self._datastore_policy(key)<EOL><DEDENT>if flag is None:<EOL><INDENT>flag = ContextOptions.use_datastore(self._conn.config)<EOL><DEDENT>if flag is None:<EOL><INDENT>flag = True<EOL><DEDENT>return flag<EOL>
Return whether to use the datastore for this key.

        Args:
          key: Key instance.
          options: ContextOptions instance, or None.

        Returns:
          True if the datastore should be used, False otherwise.