code: def run_broadcast(client):
      from xgboost.dask import _get_dask_config, _get_rabit_args
  
      workers = tm.get_client_workers(client)
      rabit_args = client.sync(
          _get_rabit_args, len(workers), _get_dask_config(), client
      )
  
      def local_test(worker_id):
          with collective.CommunicatorContext(**rabit_args):
              res = collective.broadcast(17, 0)
              return res
  
      futures = client.map(
          local_test, range(len(workers)), workers=workers
      )
      results = client.gather(futures)
      np.testing.assert_allclose(np.array(results), 17)
  
file_path: xgboost/tests/python/test_tracker.py
imports: import re
  import sys
  import numpy
  import pytest
  import xgboost
  from xgboost import RabitTracker, collective
  from xgboost import testing
label_desc: Use image node_id 5 for calling a global function with example usage: run_broadcast(client) and returns: res