code: def test_plot_theme_element_values_merged():
      spec = (
          gg.ggplot()
          + _geom("foo")
          + theme(panel_background=element_rect(color="a", fill="b"))
          + theme(panel_background=element_rect(color="c", size=1))
      )
  
      rect = spec.props()["theme"]["panel_background"]
      assert isinstance(rect, dict)
      assert "c" == rect["color"]
      assert "b" == rect["fill"]
      assert 1 == rect["size"]
  
imports: import lets_plot
  from lets_plot import element_blank
  from lets_plot import element_rect
  from lets_plot.plot import theme
  from lets_plot.plot.geom import _geom
  from lets_plot.plot.theme_set import theme_classic, flavor_darcula, flavor_solarized_dark
label_desc: Use image node_id 8 for calling a global function with example usage: test_plot_theme_element_values_merged() without return types