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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, friendly_name=values.unset, unique_name=values.unset, attributes=values.unset):
 """ Update the ChannelInstance :param unicode friendly_name: A human-readable name for the Channel. :param unicode unique_name: A unique, addressable name for the Channel. :param unicode attributes: An optional metadata field you can use to store any data you wish. :returns: Updated ChannelInstance :rtype: twilio.rest.chat.v1.service.channel.ChannelInstance """

        data = values.of({
            'FriendlyName': friendly_name,
            'UniqueName': unique_name,
            'Attributes': attributes,
        })

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

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