 extension C4Shape {
     /**
     Appends a circle to the end of the receiver's path.
+
+        var l = C4Line([C4Point(),C4Point(100,100)])
+        l.addCircle(center: l.path!.currentPoint, radius: 20)
+        canvas.add(l)
     
     :param: center The center of the new circle
     :param: radius The radius of the new circle


    /**
    Appends a polygon to the end of the receiver's path.
    
    :param: points An array of C4Point structs that defines the new polygon
    :param: closed If true then the polygon will have an additional line between its first and last points


    /**
    Appends a line segment to the end of the receiver's path.

        var l = C4Line([C4Point(),C4Point(100,100)])
        l.addLine([C4Point(100,100),C4Point(100,0)])
        canvas.add(l)

    :param: points An array of C4Point structs that defines the new line
    */
    public func addLine(points:[C4Point]) {
