code: function(r, llc) {
        return {
          x: llc.x - r.x1 + r.x2,
          y: llc.y - r.y1 + r.y2
        };
      }
docs: Get coordinates of a rectangle's lower right corner from its top points
  and its lower left corner.
  
  @param  {object} A rectangle defined by two points (x1, y1) and (x2, y2).
  @param  {object} A corner's coordinates (x, y).
  @return {object} Coordinates of the corner (x, y).