def update(self, author=values.unset, attributes=values.unset,<EOL>date_created=values.unset, date_updated=values.unset,<EOL>body=values.unset):
data = values.of({<EOL>'<STR_LIT>': author,<EOL>'<STR_LIT>': attributes,<EOL>'<STR_LIT>': serialize.iso8601_datetime(date_created),<EOL>'<STR_LIT>': serialize.iso8601_datetime(date_updated),<EOL>'<STR_LIT>': body,<EOL>})<EOL>payload = self._version.update(<EOL>'<STR_LIT:POST>',<EOL>self._uri,<EOL>data=data,<EOL>)<EOL>return MessageInstance(<EOL>self._version,<EOL>payload,<EOL>session_sid=self._solution['<STR_LIT>'],<EOL>sid=self._solution['<STR_LIT>'],<EOL>)<EOL>
Update the MessageInstance

:param unicode author: The identity of the message's author.
:param unicode attributes: A string metadata field you can use to store any data you wish.
:param datetime date_created: The date that this resource was created.
:param datetime date_updated: The date that this resource was last updated.
:param unicode body: The contents of the message.

:returns: Updated MessageInstance
:rtype: twilio.rest.messaging.v1.session.message.MessageInstance