code: def send_frame(self, cmd, headers=None, body=''):
          
          frame = utils.Frame(cmd, headers, body)
          self.transport.transmit(frame)
docs: Encode and send a stomp frame
          through the underlying transport.
  
          :param str cmd: the protocol command
          :param dict headers: a map of headers to include in the frame
          :param body: the content of the message