code: def test_unlimited_checkpoints(checkpoint_paths: List[str]):
      manager = _CheckpointManager(
          checkpoint_config=CheckpointConfig(num_to_keep=None)
      )
  
      for i in range(10):
          manager.register_checkpoint(
              _TrainingResult(
                  checkpoint=Checkpoint.from_directory(
                      checkpoint_paths[i]
                  ),
                  metrics={"iter": i},
              )
          )
  
      assert len(manager.best_checkpoint_results) == 10
  
file_path: ray/python/ray/train/tests/test_checkpoint_manager.py
imports: import random
  from pathlib import Path
  from typing import List
  import pytest
  from ray.train import Checkpoint, CheckpointConfig
  from ray.train._internal.checkpoint_manager import _CheckpointManager, _TrainingResult
label_desc: Use image node_id 2 for calling a global function with example usage: test_unlimited_checkpoints(checkpoint_paths) without return types