code: function _quadIndexes(rectangle, quadCorners) {
      var indexes = [];
  
      // Iterating through quads
      for (var i = 0; i < 4; i++)
        if ((rectangle.x2 >= quadCorners[i][0].x) &&
            (rectangle.x1 <= quadCorners[i][1].x) &&
            (rectangle.y1 + rectangle.height >= quadCorners[i][0].y) &&
            (rectangle.y1 <= quadCorners[i][2].y))
          indexes.push(i);
  
      return indexes;
    }
docs: Get a list of indexes of nodes containing an axis-aligned rectangle
  
  @param  {object}  rectangle   A rectangle defined by two points (x1, y1),
  (x2, y2) and height.
  @param  {array}   quadCorners An array of the quad nodes' corners.
  @return {array}               An array of indexes containing one to
  four integers.