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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_set(self):
 """Adds a new set to the forest. Returns a label by which the new set can be referenced """

        self.__label_counter += 1
        new_label = self.__label_counter
        self.__forest[new_label] = -1  # All new sets have their parent set to themselves
        self.__set_counter += 1
        return new_label