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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, unique_name=values.unset, data=values.unset):
 """ Create a new DocumentInstance :param unicode unique_name: The unique_name :param dict data: The data :returns: Newly created DocumentInstance :rtype: twilio.rest.preview.sync.service.document.DocumentInstance """

        data = values.of({'UniqueName': unique_name, 'Data': serialize.object(data), })

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

        return DocumentInstance(self._version, payload, service_sid=self._solution['service_sid'], )