code: def test_transform_disk():
      """Test that the transform() method works for DiskDatasets."""
      dataset = load_solubility_data()
      X = dataset.X
      y = dataset.y
      w = dataset.w
      ids = dataset.ids
  
      # Transform it
  
      transformer = TestTransformer(transform_X=True, transform_y=True)
      for parallel in (True, False):
          transformed = dataset.transform(
              transformer, parallel=parallel
          )
          np.testing.assert_array_equal(X, dataset.X)
          np.testing.assert_array_equal(y, dataset.y)
          np.testing.assert_array_equal(w, dataset.w)
          np.testing.assert_array_equal(ids, dataset.ids)
          np.testing.assert_array_equal(2 * X, transformed.X)
          np.testing.assert_array_equal(1.5 * y, transformed.y)
          np.testing.assert_array_equal(w, transformed.w)
          np.testing.assert_array_equal(ids, transformed.ids)
  
imports: import random
  import math
  import unittest
  import os
  import numpy
  import pytest
  import deepchem
  import pandas
  import tempfile
label_desc: Use image node_id 3 for calling a global function with example usage: test_transform_disk() without return types