class_docstr: Abstract class for meters used in metric stats.
  Every subclass has cached values for some metric
  
  Parameters
  ----------
  min_mode: bool or None
      if set to true, the smaller value is considered better and vice versa;
      if set to None, no optimality is defined.
code: def _initialize(self):
      pass
  
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 2 for calling the Meter obj's underlying member method code with example usage: obj._initialize() without return types