code: def list():
      db = read_checkpoint_db()
  
      if not db["checkpoints"]:
          click.echo("No checkpoints available.")
          return
  
      template = "| {:>12} | {:>21} | {:>11} | {:>6} | {:>14} |"
  
      header = template.format(
          "id", "name", "alias", "source", "status"
      )
      click.echo("=" * len(header))
      click.echo(header)
      click.echo("=" * len(header))
  
      for checkpoint in db["checkpoints"]:
          line = template.format(
              checkpoint["id"],
              checkpoint["name"],
              checkpoint["alias"],
              checkpoint["source"],
              checkpoint["status"],
          )
          click.echo(line)
  
      click.echo("=" * len(header))
  
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 15 for calling a global function with example usage: list() without return types