code: async def dump_message(self, msg, msg_type=None):
          
          mtype = msg.__class__ if msg_type is None else msg_type
          fields = mtype.f_specs()
          for field in fields:
              await self.message_field(msg=msg, field=field)
docs: Dumps message to the writer.
  
          :param msg:
          :param msg_type:
          :return: