How can i clip a rectangle with on close?

[jim-jiang-github]

This is a simple code:
` static void Main(string[] args)
{
Console.WriteLine("Hello, World!");
PointD[] pointDs = new PointD[]
{
new PointD(200,1000),
new PointD(3200,1000),
new PointD(3000,600),
new PointD(200,600),
};
PathsD psd = new PathsD();
psd.Add(new PathD(pointDs));
Point startPoint = new Point(0, 0);
double width = 15000;
double height = 1520;
int split = 500;
SvgWriter svg = new(FillRule.NonZero);

 for (int i = 0; i < (int)(width / split); i++)
 {
     var startX = i * split;
     var endX = split * i + split;
     RectD clipRect = new RectD(Math.Max(0, startX - 2), 0, endX, height);
     PathsD paths = Clipper.RectClip(clipRect, psd, 8);
     SvgUtils.AddSubject(svg, paths);
 }
 svg.SaveToFile("rectclip.svg");

}`

I want split a rectangle, I use 'Clipper.RectClip', but a got mutiple rectange splited with closed. How can I splite rectangle without close??