code: def testFlattenAndPack(self):
      structure = ((3, 4), 5, (6, 7, (9, 10), 8))
      flat = ["a", "b", "c", "d", "e", "f", "g", "h"]
      self.assertEqual(
          nest.flatten(structure), [3, 4, 5, 6, 7, 9, 10, 8]
      )
      self.assertEqual(
          nest.pack_sequence_as(structure, flat),
          (("a", "b"), "c", ("d", "e", ("f", "g"), "h")),
      )
      point = collections.namedtuple("Point", ["x", "y"])
      structure = (point(x=4, y=2), ((point(x=1, y=0),),))
      flat = [4, 2, 1, 0]
      self.assertEqual(nest.flatten(structure), flat)
      restructured_from_flat = nest.pack_sequence_as(structure, flat)
      self.assertEqual(restructured_from_flat, structure)
      self.assertEqual(restructured_from_flat[0].x, 4)
      self.assertEqual(restructured_from_flat[0].y, 2)
      self.assertEqual(restructured_from_flat[1][0][0].x, 1)
      self.assertEqual(restructured_from_flat[1][0][0].y, 0)
  
      self.assertEqual([5], nest.flatten(5))
      self.assertEqual([np.array([5])], nest.flatten(np.array([5])))
  
      self.assertEqual("a", nest.pack_sequence_as(5, ["a"]))
      self.assertEqual(
          np.array([5]),
          nest.pack_sequence_as("scalar", [np.array([5])]),
      )
  
      with self.assertRaisesRegex(
          ValueError, "Argument `structure` is a scalar"
      ):
          nest.pack_sequence_as("scalar", [4, 5])
  
      with self.assertRaisesRegex(TypeError, "flat_sequence"):
          nest.pack_sequence_as([4, 5], "bad_sequence")
  
      with self.assertRaises(ValueError):
          nest.pack_sequence_as([5, 6, [7, 8]], ["a", "b", "c"])
  
imports: import collections
  import dataclasses
  from absl.testing import parameterized
  import numpy
  from tensorflow.python.data.kernel_tests import test_base
  from tensorflow.python.data.util import nest
  from tensorflow.python.framework import combinations
  from tensorflow.python.framework import constant_op
  from tensorflow.python.framework import sparse_tensor
  from tensorflow.python.framework import tensor
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import math_ops
  from tensorflow.python.ops.ragged import ragged_factory_ops
  from tensorflow.python.platform import test
label_desc: Use image node_id 1 for calling the NestTest obj's underlying member method code with example usage: obj.testFlattenAndPack() without return types