similar to unix comm command

comm.py

#!/usr/bin/env python3

# Similar to the unix tool comm.
# Does not require input to be in sorted order.
# Defaults to finding the intersection of two lists.

import argparse

def slurp(fname):
    f = open(fname)
    data = f.read().strip().split("\n")
    if args['ignore_case']:
        data = map(str.lower, data)
    f.close()
    return set(data)


def setprint(s):
    for x in s:
        print(x)


parser = argparse.ArgumentParser(description='compare two lists')
parser.add_argument('-i','--ignore-case', help='case-insensitive comparison', action=argparse.BooleanOptionalAction, required=False, default=False)
# argparse.BooleanOptionalAction requires python version 3.9 or newer
parser.add_argument("-d", "--difference", help='find lines unique to the first file', action=argparse.BooleanOptionalAction, required=False, default=False)
parser.add_argument("files", type=str, nargs=2, help='the files to compare')
args = vars(parser.parse_args())

# TODO support more than 2 files
data0 = slurp(args['files'][0])
data1 = slurp(args['files'][1])

if args['difference']:
    print(f"[*] items in {args['files'][0]} not {args['files'][1]}:")
    setprint(data0.difference(data1))
else:
    print("[*] items common to both files:")
    setprint(data0.intersection(data1))