code: def test_automatically_find_variables_and_return_as_object(
      df_normal_dist,
  ):
      # test case 2: return variables cast as object
      transformer = EqualFrequencyDiscretiser(
          q=10, variables=None, return_object=True
      )
      X = transformer.fit_transform(df_normal_dist)
      assert X["var"].dtypes == "O"
  
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 2 for calling a global function with example usage: test_automatically_find_variables_and_return_as_object(df_normal_dist) without return types