code: def testSmallGroups(self):
      components = np.array(
          [0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0], dtype=np.int64
      )
      dataset = dataset_ops.Dataset.from_tensor_slices(components)
      dataset = dataset.group_by_window(
          key_func=lambda x: x % 2,
          reduce_func=lambda _, xs: xs.batch(4),
          window_size=4,
      )
      get_next = self.getNext(dataset)
      self.assertAllEqual([0, 0, 0, 0], self.evaluate(get_next()))
      self.assertAllEqual([1, 1, 1, 1], self.evaluate(get_next()))
      # The small outputs at the end are deterministically produced in key
      # order.
      self.assertAllEqual([0, 0, 0], self.evaluate(get_next()))
      self.assertAllEqual([1], self.evaluate(get_next()))
  
imports: from absl.testing import parameterized
  import numpy
  from tensorflow.core.lib.core import error_codes_pb2
  from tensorflow.python.data.kernel_tests import checkpoint_test_base
  from tensorflow.python.data.kernel_tests import test_base
  from tensorflow.python.data.ops import dataset_ops
  from tensorflow.python.framework import combinations
  from tensorflow.python.framework import constant_op
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import errors
  from tensorflow.python.framework import ops
  from tensorflow.python.framework import tensor_shape
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import math_ops
  from tensorflow.python.ops import string_ops
  from tensorflow.python.platform import test
label_desc: Use image node_id 8 for calling the GroupByWindowTest obj's underlying member method code with example usage: obj.testSmallGroups() without return types