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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 variable_can_be_referenced(self, key):
 """Checks whether the value of the variable can be returned by reference :param str key: Name of the variable :return: True if value of variable can be returned by reference, False else """

        key = str(key)
        return key in self.__variable_references and self.__variable_references[key]