void main() {
    while (true) {
        String command = IO.readln("Enter a command (or 'quit'): ");
        if (command == null || command.equals("quit")) {
            break;
        }
        IO.println("You said: " + command);
    }

    IO.println("Goodbye.");
}

// From Groundwork, chapter 5 (ch05-repetition), box 13.
// This example is from Groundwork, licensed CC BY-NC-SA 4.0.
// Run with: java ch05_13.java