code: def heartbeat_enabled() -> bool:
      """Returns true if DTensor heartbeat service is enabled."""
      return os.environ.get(_DT_HEARTBEAT_ENABLED, "true").lower() in (
          "true",
          "1",
      )
  
imports: import os
  from typing import List, Optional, Union
  from tensorflow.python.eager import context
  from tensorflow.python.framework import config
  from tensorflow.python.framework import device
  from tensorflow.python.util.tf_export import tf_export
label_desc: Use image node_id 10 for calling a global function with example usage: heartbeat_enabled() and returns: unknown