code: def testWindows(self):
      a = dataset_ops.Dataset.range(5).window(1)
      b = dataset_ops.Dataset.range(5, 10).window(1)
      c = a.concatenate(b).flat_map(lambda x: x)
      self.assertDatasetProduces(c, list(range(10)))
  
imports: from absl.testing import parameterized
  import numpy
  from tensorflow.python.data.experimental.ops import random_access
  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.data.ops import options
  from tensorflow.python.data.util import nest
  from tensorflow.python.framework import combinations
  from tensorflow.python.framework import errors
  from tensorflow.python.framework import tensor_shape
  from tensorflow.python.platform import test
label_desc: Use image node_id 6 for calling the ConcatenateTest obj's underlying member method code with example usage: obj.testWindows() without return types