code: def test_error_if_input_df_contains_na_in_fit(df_na):
      # test case 3: when dataset contains na, fit method
      with pytest.raises(ValueError):
          transformer = EqualFrequencyDiscretiser()
          transformer.fit(df_na)
  
file_path: feature_engine/tests/test_discretisation/test_equal_frequency_discretiser.py
imports: import pandas
  import pytest
  from sklearn.exceptions import NotFittedError
  from feature_engine.discretisation import EqualFrequencyDiscretiser
label_desc: Use image node_id 5 for calling a global function with example usage: test_error_if_input_df_contains_na_in_fit(df_na) without return types