class_docstr: Basic Loops interface.
docstr: Called when saving a model checkpoint, use to persist loop state.
  
  Returns:
      The current loop state.
code: def on_save_checkpoint(self) -> Dict:
      """Called when saving a model checkpoint, use to persist loop state.
  
      Returns:
          The current loop state.
  
      """
      return {}
  
file_path: pytorch-lightning/src/lightning/pytorch/loops/loop.py
imports: from typing import Dict, Optional
  import lightning.pytorch
  from lightning.pytorch.loops.progress import _BaseProgress
label_desc: Use image node_id 4 for calling the _Loop obj's underlying member method code with example usage: obj.on_save_checkpoint() and returns: dict