code: def test_traverse_tree(self):
      x = [{"foo": 1}, {"bar": 2}]
      traversal = traverse_util.t_identity.tree()
      self.assertEqual(list(traversal.iterate(x)), [1, 2])
      y = traversal.update(lambda x: x + x, x)
      self.assertEqual(y, [{"foo": 2}, {"bar": 4}])
  
imports: import collections
  import jax
  import jax.numpy
  import numpy
  import optax
  from absl.testing import absltest
  import flax
  from flax import traverse_util
  from flax.core import freeze
label_desc: Use image node_id 12 for calling the TraversalTest obj's underlying member method code with example usage: obj.test_traverse_tree() without return types