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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 register_handler(alias: str, handler: callable):
 """ Used to register handler at the dispatcher. :param alias: Signal alias to match handler to. :param handler: Handler. Some callable. :return: """

        if SignalDispatcher.handlers.get(alias) is None:
            SignalDispatcher.handlers[alias] = [handler]
        else:
            SignalDispatcher.handlers.get(alias).append(handler)