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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def create(self, body=values.unset, media_url=values.unset):
 """ Create a new MessageInteractionInstance :param unicode body: Message body :param unicode media_url: Reserved :returns: Newly created MessageInteractionInstance :rtype: twilio.rest.proxy.v1.service.session.participant.message_interaction.MessageInteractionInstance """

        data = values.of({'Body': body, 'MediaUrl': serialize.map(media_url, lambda e: e), })

        payload = self._version.create(
            'POST',
            self._uri,
            data=data,
        )

        return MessageInteractionInstance(
            self._version,
            payload,
            service_sid=self._solution['service_sid'],
            session_sid=self._solution['session_sid'],
            participant_sid=self._solution['participant_sid'],
        )