code: def test_find_learning_rate(self):
      find_learning_rate_model(
          self.params(),
          os.path.join(self.TEST_DIR, "test_find_learning_rate"),
          start_lr=1e-5,
          end_lr=1,
          num_batches=100,
          linear_steps=True,
          stopping_factor=None,
          force=False,
      )
  
      # It's OK if serialization dir exists but is empty:
      serialization_dir2 = os.path.join(
          self.TEST_DIR, "empty_directory"
      )
      assert not os.path.exists(serialization_dir2)
      os.makedirs(serialization_dir2)
      find_learning_rate_model(
          self.params(),
          serialization_dir2,
          start_lr=1e-5,
          end_lr=1,
          num_batches=100,
          linear_steps=True,
          stopping_factor=None,
          force=False,
      )
  
      # It's not OK if serialization dir exists and has junk in it non-empty:
      serialization_dir3 = os.path.join(
          self.TEST_DIR, "non_empty_directory"
      )
      assert not os.path.exists(serialization_dir3)
      os.makedirs(serialization_dir3)
      with open(
          os.path.join(serialization_dir3, "README.md"), "w"
      ) as f:
          f.write("TEST")
  
      with pytest.raises(ConfigurationError):
          find_learning_rate_model(
              self.params(),
              serialization_dir3,
              start_lr=1e-5,
              end_lr=1,
              num_batches=100,
              linear_steps=True,
              stopping_factor=None,
              force=False,
          )
  
      # ... unless you use the --force flag.
      find_learning_rate_model(
          self.params(),
          serialization_dir3,
          start_lr=1e-5,
          end_lr=1,
          num_batches=100,
          linear_steps=True,
          stopping_factor=None,
          force=True,
      )
  
imports: import argparse
  import os
  import pytest
  from allennlp.common import Params
  from allennlp.data import Vocabulary
  from allennlp.models import Model
  from allennlp.common.checks import ConfigurationError
  from allennlp.common.testing import AllenNlpTestCase, requires_multi_gpu
  from allennlp.commands.find_learning_rate import search_learning_rate, find_learning_rate_from_args, find_learning_rate_model, FindLearningRate
  from allennlp.training import Trainer
  from allennlp.training.util import data_loaders_from_params
label_desc: Use image node_id 2 for calling the TestFindLearningRate obj's underlying member method code with example usage: obj.test_find_learning_rate() without return types