code: def test_transparent(self):
      num_layers = 3
  
      class TransparencyMap(layer_stack.LayerStackTransparencyMapping):
          def stacked_to_flat(
              self, stacked_module_name: str, scan_idx: int
          ) -> str:
              return stacked_module_name.replace("0", str(scan_idx))
  
          def flat_to_stacked(
              self, unstacked_module_name: str
          ) -> Optional[tuple[str, int]]:
              idx = int(re.findall(r"\d+", unstacked_module_name)[0])
              return unstacked_module_name.replace(str(idx), "0"), idx
  
      def block(x: jax.Array, i: int) -> jax.Array:
          return basic.Linear(
              output_size=x.shape[-1], name=f"linear_{i}"
          )(x)
  
      def looped(x: jax.Array) -> jax.Array:
          for i in range(num_layers):
              x = block(x, i)
          return x
  
      def stacked(x: jax.Array) -> jax.Array:
          return layer_stack.layer_stack(
              num_layers=3,
              transparent=True,
              transparency_map=TransparencyMap(),
          )(lambda y: block(y, 0))(x)
  
      looped = transform.transform(looped)
      stacked = transform.transform(stacked)
  
      x = jnp.ones((2, 2))
      rng = jax.random.PRNGKey(0)
      looped_params = looped.init(rng, x)
      stacked_params = stacked.init(rng, x)
  
      self.assertEqual(
          jax.tree_util.tree_structure(looped_params),
          jax.tree_util.tree_structure(stacked_params),
      )
  
      # Use same set of params for both calls since stacked_params have different
      # value than looped params because differences in RNG splitting.
      np.testing.assert_allclose(
          looped.apply(looped_params, rng, x),
          stacked.apply(looped_params, rng, x),
          rtol=1e-6,
      )
  
imports: import functools
  import re
  from typing import Optional
  from absl.testing import absltest
  from absl.testing import parameterized
  from haiku._src import base
  from haiku._src import basic
  from haiku._src import config
  from haiku._src import initializers
  from haiku._src import layer_stack
  from haiku._src import module
  from haiku._src import multi_transform
  from haiku._src import transform
  from haiku._src import utils
  import jax
  import jax.numpy
  import numpy
  from scipy import stats
label_desc: Use image node_id 18 for calling the LayerStackTest obj's underlying member method code with example usage: obj.test_transparent() and returns: basic, x, layer_stack, stacked_module_name, unstacked_module_name,  idx