In  []: run txt2pdf.py Results/*.txt
Out []: Writing 'ResultsA_2018_04_27_13_55.txt' with 80 characters per line and
        60 lines per page...
        PDF document: 1 pages

In [] : run txt2pdf.py Results/*.txt
Out []: usage: txt2pdf.py [-h] [--font FONT] [--font-size FONT_SIZE]
              [--extra-vertical-space EXTRA_VERTICAL_SPACE]
              [--kerning KERNING] [--media MEDIA]
              [--minimum-page-length MINIMUM_PAGE_LENGTH] [--landscape]
              [--margin-left MARGIN_LEFT] [--margin-right MARGIN_RIGHT]
              [--margin-top MARGIN_TOP] [--margin-bottom MARGIN_BOTTOM]
              [--output OUTPUT] [--author AUTHOR] [--title TITLE]
              [--quiet] [--subject SUBJECT] [--keywords KEYWORDS]
              [--break-on-blanks] [--encoding ENCODING] [--page-numbers]
              [--line-numbers]
              filename
txt2pdf.py: error: unrecognized arguments: ResultsA_2018_04_27_13_57.txt
An exception has occurred, use %tb to see the full traceback.
SystemExit: 2

./txt2pdf.py Results/first_file.txt

./txt2pdf.py Results/first_file.txt Results/second_file.txt

import sh
from glob import glob
import os

# commenting line by line
def get_last_txt(path):
    return sorted(                         # sort
        glob(path + '/*.txt'),             # all files in the folder
        key=lambda f: os.stat(f).st_mtime  # by modified time
    )[-1]                                  # return the last one

sh.python('txt2pdf.py', get_last_txt("Results"))