void setup() {
  size(400, 400);
}

void draw() {
  background(0);

  for (int i = 0; i < 1600; i++) {

    int x = i%40;
    int y = i/40;
    nico(x, y);
  }
}

void nico(int X, int Y) { 

  fill(int(random(255)), 0, 0);
  rect(X*10, Y*10, 10, 10);
}