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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_cb(self, context, t, idx, userdata):
 """A sink property changed, calls request_update"""


        if t & PA_SUBSCRIPTION_EVENT_FACILITY_MASK == PA_SUBSCRIPTION_EVENT_SERVER:
            pa_operation_unref(
                pa_context_get_server_info(context, self._server_info_cb, None))

        self.request_update(context)