code: def test_warning_if_variable_cardinality_less_than_n_categories(
      df_enc_big,
  ):
      # test case 3: when the variable has low cardinality
      with pytest.warns(UserWarning):
          encoder = RareLabelEncoder(n_categories=10)
          encoder.fit(df_enc_big)
  
file_path: feature_engine/tests/test_encoding/test_rare_label_encoder.py
imports: import pandas
  import pytest
  from feature_engine.encoding import RareLabelEncoder
label_desc: Use image node_id 5 for calling a global function with example usage: test_warning_if_variable_cardinality_less_than_n_categories(df_enc_big) without return types