code: def define_distribution(worker_hosts=True, task_index=True):
      """Register distributed execution flags.
  
      Args:
        worker_hosts: Create a flag for specifying comma-separated list of workers.
        task_index: Create a flag for specifying index of task.
  
      Returns:
        A list of flags for core.py to marks as key flags.
      """
      key_flags = []
  
      if worker_hosts:
          flags.DEFINE_string(
              name="worker_hosts",
              default=None,
              help=help_wrap(
                  "Comma-separated list of worker ip:port pairs for running "
                  "multi-worker models with DistributionStrategy.  The user would "
                  "start the program on each host with identical value for this "
                  "flag."
              ),
          )
  
      if task_index:
          flags.DEFINE_integer(
              name="task_index",
              default=-1,
              help=help_wrap(
                  "If multi-worker training, the task_index of this "
                  "worker."
              ),
          )
  
      return key_flags
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from absl import flags
  import tensorflow
  from utils.flags._conventions import help_wrap
label_desc: Use image node_id 1 for calling a global function with example usage: define_distribution(worker_hosts, task_index) and returns: key_flags