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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 observe(self, algorithm):
 """Make this an observer of an algorithm """

        if self.__observing:
            raise RuntimeError('This error observer is already observing an algorithm.')
        if hasattr(algorithm, 'GetExecutive') and algorithm.GetExecutive() is not None:
            algorithm.GetExecutive().AddObserver(self.event_type, self)
        algorithm.AddObserver(self.event_type, self)
        self.__observing = True
        return