'Update the MessageInstance
:param unicode body: The body
:param unicode attributes: The attributes
:returns: Updated MessageInstance
:rtype: twilio.rest.chat.v2.service.channel.message.MessageInstance'

def update(self, body=values.unset, attributes=values.unset):

    data = values.of({'Body': body, 'Attributes': attributes})
    payload = self._version.update('POST', self._uri, data=data)
    return MessageInstance(self._version, payload, service_sid=self._solution['service_sid'], channel_sid=self._solution['channel_sid'], sid=self._solution['sid'])
