code: def test_unflatten():
      """Test than unflatten(flatten(x)) is idempotent"""
      a = {"b": 2, "c": 3}
      d = {"a": a, "d": {"e": a}}
      assert unflatten(flatten(d)) == d
  
label_desc: Use image node_id 3 for calling a global function with example usage: test_unflatten() without return types