code: def test_merge_nested(self):
      a = {"layer": {"a": [1, 2, 3]}}
      b = {"layer": {"b": {object()}}}
      c = {"layer": {"c": {"a": "b"}}}
      actual = filtering.merge(a, b, c)
      expected = {
          "layer": {
              "a": a["layer"]["a"],
              "b": b["layer"]["b"],
              "c": c["layer"]["c"],
          }
      }
      self.assertEqual(expected, actual)
  
imports: import collections
  from collections.abc import Sequence
  import itertools
  import re
  import types
  from typing import Any, Callable
  from absl.testing import absltest
  from absl.testing import parameterized
  from haiku._src import basic
  from haiku._src import data_structures
  from haiku._src import filtering
  from haiku._src import transform
  import jax
  import jax.numpy
label_desc: Use image node_id 14 for calling the FilteringTest obj's underlying member method code with example usage: obj.test_merge_nested() without return types