<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 async def send(self, payload='', action_type='', channel=None, **kwds):
 """ This method sends a message over the kafka stream. """

        # use a custom channel if one was provided
        channel = channel or self.producer_channel

        # serialize the action type for the
        message = serialize_action(action_type=action_type, payload=payload, **kwds)
        # send the message
        return await self._producer.send(channel, message.encode())