code: def test_height_width(self):
      plots = []
      for i, plot in enumerate(p()):
          plots.append(plot + theme(figure_size=(8 + i, 6 + i)))
      fn = next(filename_gen)
      with pytest.warns(PlotnineWarning):
          save_as_pdf_pages(plots, fn)
  
file_path: plotnine/tests/test_save_as_pdf_pages.py
imports: import warnings
  from pathlib import Path
  import matplotlib.pyplot
  import pytest
  from plotnine import aes, geom_text, ggplot, ggtitle, theme
  from plotnine.data import mtcars
  from plotnine.exceptions import PlotnineError, PlotnineWarning
  from plotnine.ggplot import save_as_pdf_pages
label_desc: Use image node_id 4 for calling the TestArguments obj's underlying member method code with example usage: obj.test_height_width() without return types