old_contents: /* jshint undef: true, node: true, eqeqeq: true, esnext: true */
  
  var strip = require('rpi-ws281x-native');
  strip.init(32);
  strip.setBrightness(100);
  
  var leds = [
      0,0,0,0,0,0,0,0,
      0,0,0,0,0,0,0,0,
      0,0,0,0,0,0,0,0,
      0,0,0,0,0,0,0,0xff0000    
  ];
  
  strip.render(leds);
  var interval = setInterval(function() {
      console.log('Rendering!');
      var led = leds.shift();
      leds.push(led);
      strip.render(leds);
  }, 100);
  
  setTimeout(function () {
      console.log('Stop!');
      clearInterval(interval);
      strip.reset();
  }, 10000);
  
new_contents: /* jshint undef: true, node: true, eqeqeq: true, esnext: true */
  
  var NUMBER_OF_LEDS = 32;
  var strip = require('rpi-ws281x-native');
  strip.init(NUMBER_OF_LEDS);
  strip.setBrightness(100);
  
  var leds = [
      0,0,0,0,0,0,0,0,
      0,0,0,0,0,0,0,0,
      0,0,0,0,0,0,0,0,
      0,0,0,0,0,0,0,0    
  ];
  
  // Loop every 0.1 sec: randomise an index and a colour and display it
  strip.render(leds);
  var interval = setInterval(function() {
      var randomIndex = Math.floor(Math.random() * NUMBER_OF_LEDS);
      var randomColour = Math.floor(Math.random() * 0xffffff);
      leds[randomIndex] = randomColour;
      console.log('Rendering colour ' + randomColour + ' at index ' + randomIndex);
      strip.render(leds);
  }, 100);
  
  // After 10 secondes, stop.
  setTimeout(function () {
      console.log('Stop!');
      clearInterval(interval);
      strip.reset();
  }, 10000);
  
subject: Fix random colour generation.