def get_option(first, last):
    """Get and validate the option value as integer."""
    while True:
        try:
            print()
            option = int(input("Enter an option: "))
        except ValueError:
            print("> It must be an integer number.")
            continue
        else:
            if option < first or option > last:
                print("> Unknown option. Try it again.")
                continue
        return option