code: def test_extract_features(self):
      y1 = self.model.extract_features(self.dtest)
      self.assertTrue(len(y1) == len(self.dtest))
      for feature in y1:
          self.assertEqual(len(feature), self.model.num_trees)
  
imports: from __future__ import print_function
  from __future__ import division
  from __future__ import absolute_import
  import unittest
  import turicreate
  import math
  import uuid
  import random
  import sys
  import copy
  from turicreate.toolkits import evaluation
  from turicreate.toolkits._main import ToolkitError
  import shutil
  import numpy
  from array import array
  import os
label_desc: Use image node_id 11 for calling the RandomForestClassifierTest obj's underlying member method code with example usage: obj.test_extract_features() without return types