def __add__(self, other: "Mean") -> "Mean":
        """
        Return a metric representing the weighted mean of the 2 means.

        :param other: the other mean
        :return: The weighted mean"""
        res = Mean()
        res.summed = self.summed + other.summed
        res.weight = self.weight + other.weight
        return res

        Return a metric representing the weighted mean of the 2 means.

        :param other: the other mean
        :return: The weighted mean
avalanche/evaluation/metrics/mean.py