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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, language=values.unset, tagged_text=values.unset, source_channel=values.unset):
 """ Update the SampleInstance :param unicode language: The ISO language-country string that specifies the language used for the sample :param unicode tagged_text: The text example of how end users might express the task :param unicode source_channel: The communication channel from which the sample was captured :returns: Updated SampleInstance :rtype: twilio.rest.autopilot.v1.assistant.task.sample.SampleInstance """

        return self._proxy.update(language=language, tagged_text=tagged_text, source_channel=source_channel, )