code: def test_theme_xkcd(self):
      p = (
          self.g
          + labs(title="Theme Xkcd")
          + theme_xkcd()
          # High likely hood of Comic Sans being available
          + theme(text=element_text(family=["Comic Sans MS"]))
      )
  
      if os.environ.get("CI") or os.environ.get("TRAVIS"):
          # Github Actions and Travis do not have the fonts,
          # we still check to catch any other errors
          assert p != "theme_gray"
      else:
          assert p == "theme_xkcd"
  
imports: import os
  import pytest
  from plotnine import aes, element_blank, element_line, element_text, facet_grid, facet_wrap, geom_blank, geom_point, ggplot, labs, theme, theme_538, theme_bw, theme_classic, theme_dark, theme_gray, theme_light, theme_linedraw, theme_matplotlib, theme_minimal, theme_seaborn, theme_tufte, theme_void, theme_xkcd
  from plotnine.data import mtcars
label_desc: Use image node_id 13 for calling the TestThemes obj's underlying member method code with example usage: obj.test_theme_xkcd() without return types