code: def test_identity(self):
      id_transformer = IdentityTransformer()
      X0 = id_transformer.fit_transform_one_feature(
          self.X, 0, center=False
      ).ravel()
      assert_array_equal(X0, self.X[:, 0])
      X_transformed = id_transformer.fit_transform(self.X, center=False)
      assert_array_equal(X_transformed.get_all_data(), self.X)
  
imports: import copy
  import numpy
  import random
  import scipy
  from sklearn.linear_model import Ridge, LinearRegression
  from sklearn.tree import DecisionTreeRegressor
  from sklearn.ensemble import RandomForestRegressor, RandomForestClassifier
  from sklearn.metrics import r2_score, log_loss, roc_auc_score, mean_squared_error
  from imodels.importance.block_transformers import IdentityTransformer, TreeTransformer, CompositeTransformer, MDIPlusDefaultTransformer
  from imodels.importance.ppms import RidgeRegressorPPM, LogisticClassifierPPM, RobustRegressorPPM
  from imodels.importance.mdi_plus import TreeMDIPlus, ForestMDIPlus
  from imodels.importance.rf_plus import RandomForestPlusClassifier
label_desc: Use image node_id 2 for calling the TestTransformers obj's underlying member method code with example usage: obj.test_identity() without return types