code: def read_checkpoint_db():
      """Reads the checkpoints database file from disk."""
      path = os.path.join(get_checkpoints_directory(), CHECKPOINT_INDEX)
      if not os.path.exists(path):
          return {"checkpoints": []}
  
      with open(path) as f:
          index = json.load(f)
  
      return index
  
imports: import click
  import json
  import os
  import shutil
  import six
  import requests
  import tarfile
  import tempfile
  import tensorflow
  import uuid
  from datetime import datetime
  from luminoth import __version__
  from luminoth.utils.config import get_config
  from luminoth.utils.homedir import get_luminoth_home
label_desc: Use image node_id 3 for calling a global function with example usage: read_checkpoint_db() and returns: index, dict