code: def test_horovod_example(ray_start_4_cpus):
      from ray.tests.horovod.horovod_example import main
  
      kwargs = {
          "data_dir": "./data",
          "num_epochs": 1,
      }
  
      main(num_workers=1, use_gpu=False, kwargs=kwargs)
  
file_path: ray/python/ray/tests/horovod/test_horovod.py
imports: import pytest
  import torch
  import ray
  from ray.util.client.ray_client_helpers import ray_start_client_server
label_desc: Use image node_id 4 for calling a global function with example usage: test_horovod_example(ray_start_4_cpus) without return types