def update_cb(self, context, t, idx, userdata):
if t & PA_SUBSCRIPTION_EVENT_FACILITY_MASK == PA_SUBSCRIPTION_EVENT_SERVER:<EOL><INDENT>pa_operation_unref(<EOL>pa_context_get_server_info(context, self._server_info_cb, None))<EOL><DEDENT>self.request_update(context)<EOL>
A sink property changed, calls request_update