// Learning Processing
  // Daniel Shiffman
  // http://www.learningprocessing.com
  
  // Example 13-1: Modulo
  
  // 4 random numbers
  float[] randoms = new float[4];
  // Which number are we using
  int index = 0; 
  
  void setup() {
    size(200,200);
    
    // Fill array with random values
    for (int i = 0; i < randoms.length; i ++ ) {
      randoms[i] = random(0,256);
    }
    
    frameRate(1);
  }
  
  void draw() {
    
    // Every frame we access one element of the array
    background(randoms[index]);
    
    // And then go on to the next one
    index = (index + 1) % randoms.length; // Using the modulo operator to cycle a counter back to 0.
  }