Pairs RFID cards with their barcodes

card_pair.py

import os
output_file = "card_pairs.csv"

magic_number = 6

if output_file not in os.listdir('.'):
    with open(output_file, "w") as f:
        f.write("id_number,card_serial\n")

def do_the_thing():
    
    a = input("scan card: ")
    b = input("waiting for second input: ")

    if len(a) > magic_number:
        card_serial = a
        id_number = b
    else:
        card_serial = b
        id_number = a

    if a == b:
        print("##########")
        print("Error, same number twice!")
        print("##########\n")
        return

    print("ID: {}\nSerial: {}".format(id_number, card_serial))

    with open(output_file, "a") as f:
        f.write("{},{}\n".format(id_number,card_serial))

    print("\n\n")

while 1:
    do_the_thing()