code: def testValidNamedTuple(self):
      t = structural_tuple.structtuple(["a", "b", "c"])
      inst = t(a=1, b=2, c=3)
      a, b, c = inst
      self.assertAllEqualNested((1, 2, 3), (a, b, c))
      self.assertAllEqualNested(
          t(2, 3, 4), tf.nest.map_structure(lambda x: x + 1, inst)
      )
      inst2 = inst._replace(a=2)
      self.assertAllEqualNested(t(2, 2, 3), inst2)
      self.assertTrue(nest._is_namedtuple(inst))
  
imports: import tensorflow.compat.v2
  from tensorflow_probability.python.internal import nest_util
  from tensorflow_probability.python.internal import structural_tuple
  from tensorflow_probability.python.internal import test_util
  from tensorflow.python.util import nest
label_desc: Use image node_id 3 for calling the StructTupleTest obj's underlying member method code with example usage: obj.testValidNamedTuple() without return types