code: def test_placement_group_no_cpu_trainer():
      """Bundles with only GPU:1 but no CPU should work"""
      ray.init(num_gpus=1, num_cpus=1)
      pgf = PlacementGroupFactory([{"GPU": 1, "CPU": 0}, {"CPU": 1}])
  
      def train_fn(config):
          time.sleep(1)
          return 5
  
      tune.run(train_fn, resources_per_trial=pgf)
  
imports: import sys
  import os
  import time
  import numpy
  import unittest
  import ray
  from ray import tune
  from ray.tune.execution.ray_trial_executor import RayTrialExecutor
  from ray.tune.experiment import Trial
  from ray.tune import Callback
  from ray.tune.execution.trial_runner import TrialRunner
  from ray.tune.execution.placement_groups import PlacementGroupFactory
  from ray.util import placement_group_table
  from ray.cluster_utils import Cluster
  from ray.rllib import _register_all
label_desc: Use image node_id 1 for calling a global function with example usage: test_placement_group_no_cpu_trainer() and returns: int