code: def test_multi_layer(data_dir):
      layerdef = "1:coutwildrnp,1:coutwildrnp"
      runner = CliRunner()
      result = runner.invoke(
          main_group, ["cat", "--layer", layerdef, data_dir]
      )
      assert result.output.count('"Feature"') == 134
  
file_path: Fiona/tests/test_fio_cat.py
imports: from click.testing import CliRunner
  from fiona.fio.main import main_group
label_desc: Use image node_id 12 for calling a global function with example usage: test_multi_layer(data_dir) without return types