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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 _add_function(self, func, identify_observed):
 """Add a function as an observer. Args: func: The function to register as an observer. identify_observed: See docstring for add_observer. Returns: True if the function is added, otherwise False. """


        key = self.make_key(func)
        if key not in self.observers:
            self.observers[key] = ObserverFunction(
                func, identify_observed, (key, self.observers))
            return True
        else:
            return False