def __init__(self):
        """
        Creates an instance of the mean metric.

        This metric in its initial state will return a mean value of 0.
        The metric can be updated by using the `update` method while the mean
        can be retrieved using the `result` method.
        """
        self.summed: float = 0.0
        self.weight: float = 0.0

        Creates an instance of the mean metric.

        This metric in its initial state will return a mean value of 0.
        The metric can be updated by using the `update` method while the mean
        can be retrieved using the `result` method.
        
avalanche/evaluation/metrics/mean.py