code: def rotate_even_pages_180(input_filename: str, output_filename: str) -> str:
      
      log.info("Rotating even-numbered pages 180 degrees for long-edge "
               "duplex printing")
      log.debug("... {!r} -> {!r}", input_filename, output_filename)
      require(PDFTK, HELP_MISSING_PDFTK)
      args = [
          PDFTK,
          "A=" + input_filename,  # give it handle 'A'
          # handles are one or more UPPER CASE letters
          "shuffle",
          "Aoddnorth",  # for 'A', keep odd pages as they are
          "Aevensouth",  # for 'A', rotate even pages 180 degrees
          "output", output_filename,
      ]
      run(args)
      return output_filename
docs: Rotates even-numbered pages 180 degrees.
      Returns the output filename.