code: def test_dpi_theme_xkcd(self):
      fn1 = next(filename_gen)
      fn2 = next(filename_gen)
  
      data = pd.DataFrame(
          {"x": range(4), "y": range(4), "b": list("aabb")}
      )
  
      p = (
          ggplot(data)
          + geom_point(aes("x", "y"))
          + facet_wrap("b")
          + theme_xkcd()
      )
      p.save(fn1, verbose=False)
      assert_exist_and_clean(fn1, "Saving with theme_xkcd and dpi (1)")
  
      p.save(fn2, dpi=72, verbose=False)
      assert_exist_and_clean(fn2, "Saving with theme_xkcd and dpi (2)")
  
imports: import warnings
  from pathlib import Path
  import matplotlib.pyplot
  import pandas
  import pytest
  from plotnine import aes, facet_wrap, geom_point, geom_text, ggplot, ggsave, theme_xkcd
  from plotnine.data import mtcars
  from plotnine.exceptions import PlotnineError, PlotnineWarning
label_desc: Use image node_id 8 for calling the TestArguments obj's underlying member method code with example usage: obj.test_dpi_theme_xkcd() without return types