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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 stop(self):
 """ Stop the client. This sends a signal to the clients main task which makes it terminate. It may take some cycles through the event loop to stop the client task. To check whether the task has actually stopped, query :attr:`running`. """

        if not self.running:
            return

        self.logger.debug("stopping main task of %r", self, stack_info=True)
        self._main_task.cancel()