code: def test_classifier_all_variables(df_regression):
      X, y = df_regression
  
      tr = TargetMeanRegressor(bins=2)
      tr.fit(X, y)
  
      pred = tr.predict(X)
  
      exp_pred = np.array(
          [
              0.34166667,
              0.34166667,
              0.34166667,
              0.34166667,
              0.34166667,
              0.59166667,
              0.925,
              0.925,
              1.325,
              1.325,
              1.675,
              1.675,
              2.075,
              2.075,
              2.40833333,
              2.65833333,
              2.65833333,
              2.65833333,
              2.65833333,
              2.65833333,
          ]
      )
  
      assert np.allclose(pred, exp_pred)
  
imports: import numpy
  from feature_engine._prediction.target_mean_regressor import TargetMeanRegressor
label_desc: Use image node_id 3 for calling a global function with example usage: test_classifier_all_variables(df_regression) without return types