anchor.diff:    /**
      * Speed of gravity.
      */
  -  int speed = 0;
  +  num speed = 0;
   
     /**
      * Gravity's [DirectionSystem].
  
positive.code: 
    /**
     * Set the gravity's direction.
     * 
     * Direction can be: up/forward, down/backward, left, right
     */
    void setDirection(String direction) {
  
negative.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() {
  