anchor.diff:  
     /**
      * Set the gravity's direction.
  -   * 
  +   *
      * Direction can be: up/forward, down/backward, left, right
      */
     void setDirection(String direction) {
  
positive.code: 
    /**
     * Set the gravity's direction to zero vector.
     * 
     * This means the gravity wont have a direction and this means there will be no gravity.
     */
    void nullDirection() {
  
negative.code:   void rotateDirectionsRads(num radians) {
      directionSystem.rotateDirectionsRadians(radians);
    }
  
    StageXL.Vector getVelocity() {
      return directionSystem.mainDirection.scale(speed);
    }
  