class_docstr: Class for global accumulation state. add_stats gets reduced.
code: def __init__(self, rpc_group, global_stats):
      self.rpc_group = rpc_group
      self.global_stats = global_stats
      self.reduce_future = None
      self.queued_global_stats = None
      self.sent_global_stats = None
      self.prev_stats = None
  
imports: import copy
  import dataclasses
  import logging
  import torch
  import moolib
label_desc: Use image node_id 1 to create a new GlobalStatsAccumulator object  with example: obj = GlobalStatsAccumulator(rpc_group, global_stats)