code: def test_layout_empty_subplots(self):
      layout = (
          Curve(range(10))
          + NdOverlay()
          + HoloMap()
          + HoloMap({1: Image(np.random.rand(10, 10))})
      )
      plot = mpl_renderer.get_plot(layout)
      self.assertEqual(len(plot.subplots.values()), 2)
      self.log_handler.assertContains("WARNING", "skipping subplot")
      self.log_handler.assertContains("WARNING", "skipping subplot")
  
file_path: holoviews/holoviews/tests/plotting/matplotlib/test_layoutplot.py
imports: import numpy
  from holoviews.core import DynamicMap, HoloMap, NdOverlay
  from holoviews.element import Curve, Image
  from holoviews.streams import Stream
  from ...utils import LoggingComparisonTestCase
  from .test_plot import TestMPLPlot, mpl_renderer
label_desc: Use image node_id 2 for calling the TestLayoutPlot obj's underlying member method code with example usage: obj.test_layout_empty_subplots() without return types