code: function QT_ARRAY_POP(bounds, max_objects, max_levels, level) {
         if (QT_ARRAY.length > 0) {
           var _qt = QT_ARRAY.pop();
  
           _qt.bounds = bounds;
           _qt.max_objects = max_objects || 4;
           _qt.max_levels = max_levels || 4;
           _qt.level = level || 0;
           return _qt;
         } else {
           return new me.QuadTree(bounds, max_objects, max_levels, level);
         }
       }
docs: will pop a quadtree object from the array
  or create a new one if the array is empty