code: def test_contours():
      p = p0 + geom_density_2d(aes(color=after_stat("level")))
      assert p == "contours"
  
imports: import pandas
  from plotnine import aes, after_stat, geom_density_2d, geom_point, ggplot, lims, scale_size_radius, stat_density_2d
label_desc: Use image node_id 1 for calling a global function with example usage: test_contours() without return types