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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 start_tracing(self, tid):
 """ Start tracing mode in the given thread. @type tid: int @param tid: Global ID of thread to start tracing. """

        if not self.is_tracing(tid):
            thread = self.system.get_thread(tid)
            self.__start_tracing(thread)