code: def test_null_transformer3(data):
      """Checks impute_algorithm=None"""
      # impute_algorithm=None is the default
      null_transform = NullTransformer(impute_all=False)
      null_transform.fit(data)
      assert null_transform.impute_params is None
      result = null_transform.transform(data)
      assert_equal(result, data)
  
      # impute_all=True has no effect
      null_transform = NullTransformer(
          impute_algorithm=None, impute_all=True
      )
      null_transform.fit(data)
      assert null_transform.impute_params is None
      result = null_transform.transform(data)
      assert_equal(result, data)
  
file_path: greykite/greykite/tests/sklearn/transform/test_null_transformer.py
imports: import numpy
  import pandas
  import pytest
  from sklearn.exceptions import NotFittedError
  from testfixtures import LogCapture
  from greykite.common.constants import LOGGER_NAME
  from greykite.common.python_utils import assert_equal
  from greykite.sklearn.transform.null_transformer import NullTransformer
label_desc: Use image node_id 4 for calling a global function with example usage: test_null_transformer3(data) without return types