class_docstr: Call the callback function with epoch # when the epoch ends
class_docstr_tok: ["Call","the","callback","function","with","epoch","#","when","the","epoch","ends"]
code: def __init__(self, callback, key: str = "epoch_end"):
      super().__init__(observing_keys=[key])
      self.callback = callback
  
imports: import logging
  from typing import Any, Dict, Iterable, List, Optional
  from reagent.core.tensorboardX import SummaryWriterContext
  from reagent.core.tracker import Aggregator, Observer
label_desc: Use image node_id 1 to create a new EpochEndObserver object from inherited base classes: Observer with example: obj = EpochEndObserver(callback, key)