anchor.diff:     *      });
      * 
      */
  -  void collison(var object1, var object2, Function
  -      collisonHandler(item1, itme2)) {
  +  void collison(var object1, var object2, Function collisonHandler(item1,
  +      itme2)) {
   
       if (object1 is Group && object2 is Group) {
   
  
positive.code: 
    }
  
  }
  
negative.code:  */
  
  class Physics {
  
    num garvitySpeed = 0;
  
    StageXL.Vector gravityDirection = new StageXL.Vector.zero();
  
    StageXL.Vector upDirection = new StageXL.Vector(0, -1);
    StageXL.Vector downDirection = new StageXL.Vector(0, 1);
    StageXL.Vector leftDirection = new StageXL.Vector(-1, 0);
    StageXL.Vector rightDirection = new StageXL.Vector(1, 0);
  
    /**
     * Resolve collison between two gameobject.
     * 
  