code: def make_blank_pdf(filename: str, paper: str = "A4") -> None:
      
      # https://unix.stackexchange.com/questions/277892/how-do-i-create-a-blank-pdf-from-the-command-line  # noqa
      require(CONVERT, HELP_MISSING_IMAGEMAGICK)
      run([CONVERT, "xc:none", "-page", paper, filename])
docs: NOT USED.
      Makes a blank single-page PDF, using ImageMagick's ``convert``.