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

        This metric in its initial state (or if the `update` method was invoked
        only once) will return an elapsed time of 0. The metric can be updated
        by using the `update` method while the running accuracy can be retrieved
        using the `result` method.
        """
        self._init_time = None
        self._prev_time = None

        Creates an instance of the ElapsedTime metric.

        This metric in its initial state (or if the `update` method was invoked
        only once) will return an elapsed time of 0. The metric can be updated
        by using the `update` method while the running accuracy can be retrieved
        using the `result` method.
        
avalanche/evaluation/metrics/timing.py