code: def test_leaf_components_combination_kernel() -> None:
      """
      Regression test for kernel compositions - output for printing should not be empty (issue #1066).
      """
      k = (
          gpflow.kernels.SquaredExponential()
          + gpflow.kernels.SquaredExponential()
      )
      assert leaf_components(
          k
      ), "Combination kernel should have non-empty leaf components"
  
imports: from typing import Any, Callable, Mapping, Optional, Type
  import numpy
  import pytest
  import tensorflow
  from _pytest.fixtures import SubRequest
  from packaging.version import Version
  import gpflow
  from gpflow.base import AnyNDArray
  from gpflow.config import Config, as_context
  from gpflow.utilities import set_trainable
  from gpflow.utilities.traversal import _merge_leaf_components, leaf_components, tabulate_module_summary
label_desc: Use image node_id 14 for calling a global function with example usage: test_leaf_components_combination_kernel() without return types