code: def test_scale(self):
      iris = datasets.load_iris()
      df = pdml.ModelFrame(iris)
  
      result = df.preprocessing.scale()
      expected = pp.scale(iris.data)
  
      self.assertIsInstance(result, pdml.ModelFrame)
      self.assert_numpy_array_almost_equal(result.data.values, expected)
      tm.assert_index_equal(result.columns, df.data.columns)
  
      s = df["sepal length (cm)"]
      self.assertIsInstance(s, pdml.ModelSeries)
      result = s.preprocessing.scale()
      expected = pp.scale(np.atleast_2d(iris.data[:, 0]))[0]
  
      self.assertIsInstance(result, pdml.ModelSeries)
      self.assert_numpy_array_almost_equal(result.values, expected)
      self.assertEqual(result.name, "sepal length (cm)")
  
imports: import pytest
  import numpy
  import pandas
  import sklearn.datasets
  import sklearn.preprocessing
  import pandas_ml
  import pandas_ml.util.testing
label_desc: Use image node_id 6 for calling the TestPreprocessing obj's underlying member method code with example usage: obj.test_scale() without return types