SimonSapin

    #[lang = "panic_fmt"]
    extern fn panic_fmt(details: ::core::fmt::Arguments, file: &'static str, line: u32) -> ! {
        println!("Panic at {}:{}, {}", file, line, details);
        let row_2 = ::gpio::Pin::output(::pins::ROW_2);
        let col_3 = ::gpio::Pin::output(::pins::COL_3);
        row_2.set_high();
        loop {
            col_3.set_low();
            ::busy_loop::wait_approx_ms(5);
            col_3.set_high();
            ::busy_loop::wait_approx_ms(200);
        }
    }