def check_empty_response(self, orig_request, method_config, start_response):
    """If the response from the backend is empty, return a HTTP 204 No Content.

    Args:
      orig_request: An ApiRequest, the original request from the user.
      method_config: A dict, the API config of the method to be called.
      start_response: A function with semantics defined in PEP-333.

    Returns:
      If the backend response was empty, this returns a string containing the
      response body that should be returned to the user.  If the backend
      response wasn't empty, this returns None, indicating that we should not
      exit early with a 204.
    """
    response_config = method_config.get('response', {}).get('body')
    if response_config == 'empty':
      # The response to this function should be empty.  We should return a 204.
      # Note that it's possible that the backend returned something, but we'll
      # ignore it.  This matches the behavior in the Endpoints server.
      cors_handler = self._create_cors_handler(orig_request)
      return util.send_wsgi_no_content_response(start_response, cors_handler)
If the response from the backend is empty, return a HTTP 204 No Content.

    Args:
      orig_request: An ApiRequest, the original request from the user.
      method_config: A dict, the API config of the method to be called.
      start_response: A function with semantics defined in PEP-333.

    Returns:
      If the backend response was empty, this returns a string containing the
      response body that should be returned to the user.  If the backend
      response wasn't empty, this returns None, indicating that we should not
      exit early with a 204.