code: def test_tuner_with_already_configured_learning_rate_finder():
      """Test that an error is raised when tuner is already configured with LearningRateFinder."""
      trainer = Trainer(callbacks=[LearningRateFinder()])
      tuner = Tuner(trainer)
      model = BoringModel()
  
      with pytest.raises(
          ValueError,
          match=r"Trainer is already configured with a `LearningRateFinder`",
      ):
          tuner.lr_find(model)
  
file_path: pytorch-lightning/tests/tests_pytorch/tuner/test_tuning.py
imports: import pytest
  from lightning.pytorch import Trainer
  from lightning.pytorch.callbacks import BatchSizeFinder, LearningRateFinder
  from lightning.pytorch.demos.boring_classes import BoringModel
  from lightning.pytorch.tuner.tuning import Tuner
label_desc: Use image node_id 3 for calling a global function with example usage: test_tuner_with_already_configured_learning_rate_finder() without return types