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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 unregister(self, signal):
 """ Unregisters an existing signal :param signal: Name of the signal """

        if signal in self.signals.keys():
            del(self.signals[signal])
            self.__log.debug("Signal %s unregisterd" % signal)
        else:
            self.__log.debug("Signal %s does not exist and could not be unregistered.")