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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 update(self, unique_name=values.unset):
 """ Update the ModelBuildInstance :param unicode unique_name: An application-defined string that uniquely identifies the resource :returns: Updated ModelBuildInstance :rtype: twilio.rest.autopilot.v1.assistant.model_build.ModelBuildInstance """

        return self._proxy.update(unique_name=unique_name, )