code: def test_repr(ray_start_4_cpus):
      def training_loop(self):
          pass
  
      trainer = DummyTrainer(
          training_loop,
          datasets={
              "train": ray.data.from_items([1, 2, 3]),
          },
      )
  
      representation = repr(trainer)
  
      assert "DummyTrainer" in representation
      assert len(representation) < MAX_REPR_LENGTH
  
imports: import logging
  import tempfile
  import pytest
  import ray
  from ray import train, tune
  from ray.air.constants import MAX_REPR_LENGTH
  from ray.data.context import DataContext
  from ray.train import Checkpoint, ScalingConfig
  from ray.train.gbdt_trainer import GBDTTrainer
  from ray.train.trainer import BaseTrainer
  from ray.util.placement_group import get_current_placement_group
label_desc: Use image node_id 7 for calling a global function with example usage: test_repr(ray_start_4_cpus) without return types