import argparse
from pathlib import Path

def encrypt(file):
    sal = 'hello encryption'
    return sal


def decrypt(file):
    greet = 'hello decryption'
    return greet


def main():
    parser = argparse.ArgumentParser()
    parser.add_argument('-f', '--file', type=open)
    parser.add_argument('modality', choices=['encrypt', 'decrypt'])
    args = parser.parse_args()

    if args.modality == 'encrypt':
        print(encrypt(args.file))
    elif args.modality == 'decrypt':
        print(decrypt(args.file))

if __name__ == '__main__':
    main()