<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def payload(self, value):
 """ Sets the payload of the message and eventually the Content-Type :param value: the payload """

        if isinstance(value, tuple):
            content_type, payload = value
            self.content_type = content_type
            self._payload = payload
        else:
            self._payload = value