code: def _update_from_body(self, destination, source):
      
      for key, value in source.iteritems():
        destination_value = destination.get(key)
        if isinstance(value, dict) and isinstance(destination_value, dict):
          self._update_from_body(destination_value, value)
        else:
          destination[key] = value
docs: Updates the dictionary for an API payload with the request body.
  
      The values from the body should override those already in the payload, but
      for nested fields (message objects) the values can be combined
      recursively.
  
      Args:
        destination: A dictionary containing an API payload parsed from the
          path and query parameters in a request.
        source: A dictionary parsed from the body of the request.