code: def on_stats(
      self,
      index: int,
      eval_stats_before: Optional[Stats] = None,
      train_stats: Optional[Stats] = None,
      eval_stats_after: Optional[Stats] = None,
      eval_stats_chunk_avg: Optional[Stats] = None,
  ) -> None:
      pass
  
file_path: PyTorch-BigGraph/torchbiggraph/stats.py
imports: from collections import defaultdict
  from statistics import mean
  from typing import cast, Dict, Iterable, Optional, Type, Union
  from torchbiggraph.types import FloatTensorType
label_desc: Use image node_id 1 for calling the StatsHandler obj's underlying member method code with example usage: obj.on_stats(index, eval_stats_before, train_stats, eval_stats_after, eval_stats_chunk_avg) without return types