Comment by ahoge

Dart:

  import 'dart:async';
  import 'dart:io';
  main() {
    var file = new File('/sys/class/leds/beaglebone:green:usr0/brightness');
    var state = 0;
    new Timer.periodic(new Duration(seconds: 2), (_) {
      state = 1 - state;
      file.writeAsStringSync('0$state', flush: true);
    });
  }

While it's not the most concise version, it's certainly very readable. Everyone can clearly see that the duration is 2 seconds and that that boolean flag is for flushing, because that's exactly what the code says.