code: def test_non_fitted_error(df_enc):
      with pytest.raises(NotFittedError):
          encoder = DecisionTreeEncoder()
          encoder.transform(df_enc)
  
file_path: feature_engine/tests/test_encoding/test_decision_tree_encoder.py
imports: import numpy
  import pandas
  import pytest
  from sklearn.exceptions import NotFittedError
  from feature_engine.encoding import DecisionTreeEncoder
label_desc: Use image node_id 4 for calling a global function with example usage: test_non_fitted_error(df_enc) without return types