code: def test_broadcast():
      from distributed import Client, LocalCluster
  
      n_workers = 3
      with LocalCluster(n_workers=n_workers) as cluster:
          with Client(cluster) as client:
              run_broadcast(client)
  
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 6 for calling a global function with example usage: test_broadcast() without return types