DouKaku?

private import std.stdio, std.c.time;

void main() {
    bool running = true;
    for(;;) {
        sleep(1);
        if(kbhit) {
            switch(getch) {
                case 'p':
                    running = !running;
                    break;
                case 'q':
                    return;
                default:
            }
        }
        if(running) {
            write('a');
            fflush(stdout);
        }
    }
}