import os
import pathlib
from glob import glob
import subprocess
files = dict(sorted((int(file.name[4:-12]), file) for file in pathlib.Path('.').rglob('week*-handout.pdf')))
fileList = map(lambda x: f'\"{str(x)}\"', files.values())
command = f"pdftk {' '.join(fileList)} cat output handout.pdf"
subprocess.run(command)