class_docstr: Test some basic splitters.
docstr: Test that we can 5 fold index wise over 5 points
code: def test_k_fold_splitter(self):
      """
      Test that we can 5 fold index wise over 5 points
      """
      ds = NumpyDataset(np.array(range(5)), np.array(range(5)))
      index_splitter = IndexSplitter()
  
      K = 5
      fold_datasets = index_splitter.k_fold_split(ds, K)
  
      for fold in range(K):
          train, cv = fold_datasets[fold][0], fold_datasets[fold][1]
          self.assertTrue(cv.X[0] == fold)
          train_data = set(list(train.X))
          self.assertFalse(fold in train_data)
          self.assertEqual(K - 1, len(train))
          self.assertEqual(1, len(cv))
  
imports: import os
  import unittest
  import numpy
  import deepchem
  from deepchem.data import NumpyDataset
  from deepchem.splits import IndexSplitter
label_desc: Use image node_id 9 for calling the TestSplitter obj's underlying member method code with example usage: obj.test_k_fold_splitter() without return types