def __init__(self, class_names=None):
        """
        :param class_names: list of names for the classes.
            E.g. ["cat", "dog"] if class 0 == "cat" and class 1 == "dog"
            If None, no class names will be used. Default None.
        """

        super().__init__()

        self.outputs = []  # softmax-ed or logits outputs
        self.targets = []  # target classes
        self.class_names = class_names

        :param class_names: list of names for the classes.
            E.g. ["cat", "dog"] if class 0 == "cat" and class 1 == "dog"
            If None, no class names will be used. Default None.
        
avalanche/evaluation/metrics/confusion_matrix.py