which command for windows, place it on PATH and include '.py' in PATHEXT

which.py

import shutil, sys
try:
    result = shutil.which(sys.argv[1])
    print(result if result else f"unable to find '{sys.argv[1]}'")
except IndexError:
    print("not enough arguments", file=sys.stderr)
except Exception as e:
    print("an unknown error occured:", e, file=sys.stderr)