class_docstr: Maintains running average for scalar metrics
  
  Call .restart() to clear added values and to start a new round of averaging
code: def _initialize(self) -> None:
      self._cum_values = 0.0
      self._count = 0
      self.cache = 0.0
  
imports: from __future__ import annotations
  import time
  import warnings
  from abc import ABC, abstractmethod
  from typing import Optional, Union
  from torch import Tensor
  from ..engine.distributed import reduce_value
label_desc: Use image node_id 1 for calling the NumericalAverageMeter obj's underlying member method code with example usage: obj._initialize() without return types