code: function Dust() {
    Vector.apply( this, arguments ); // call Vector's constructor
    this.age = 0;
    this.maxAge = Math.random() * 500 + 50;
    this.weight =  0.25 + Math.random()*3;
    this.color = (this.weight > 0.7) ? colors["a"+Math.ceil(Math.random()*4)] : "#000";
  }
docs: // 2. Create Elements A Dust is a kind of Vector