var RotateAround = function (point, x, y, angle){ 
var c = Math.cos(angle); 
var s = Math.sin(angle); 
var tx = point.x - x; 
var ty = point.y - y; 
point.x = tx * c - ty * s + x; 
point.y = tx * s + ty * c + y; 
return point; 
} 
; 
module.exports = RotateAround;