code: def handle_ping(self, message_header, message):
          
          log.debug("handle ping")
          pong = Pong()
          pong.nonce = message.nonce
          log.debug("send pong")
          self.send_message(pong)
docs: This method will handle the Ping message and then
          will answer every Ping message with a Pong message
          using the nonce received.
  
          :param message_header: The header of the Ping message
          :param message: The Ping message