Function for retrieving the wanted day

def get_day():
    """Function for retrieving the wanted day"""
    day = datetime.datetime.today().weekday()
    if len(sys.argv) == 3:
        if sys.argv[2] == "mon":
            day = 0
        elif sys.argv[2] == "tue":
            day = 1
        elif sys.argv[2] == "wed":
            day = 2
        elif sys.argv[2] == "thur":
            day = 3
        elif sys.argv[2] == "fri":
            day = 4
        else:
            day = 5
    if day > 4:
        print("There is no information about the menu today.")
        exit(5)
    return day