code: def test_bivariate_composite_empty_filled(self):
      dist = Bivariate([]).opts(filled=True)
      contours = Compositor.collapse_element(dist, backend="matplotlib")
      assert isinstance(contours, Polygons)
      assert contours.vdims == [Dimension("Density")]
      assert len(contours) == 0
  
imports: import numpy
  import pandas
  import pytest
  from holoviews.core.dimension import Dimension
  from holoviews.core.options import Compositor, Store
  from holoviews.element import Area, Bivariate, Contours, Curve, Distribution, Image, Points, Polygons
label_desc: Use image node_id 13 for calling the TestStatisticalCompositor obj's underlying member method code with example usage: obj.test_bivariate_composite_empty_filled() without return types