func app(context *httpcanvas.Context) { centerX := context.Width / 2 centerY := context.Height / 2 context.BeginPath() context.Arc(centerX, centerY, 70, 0, 2*math.Pi, false) context.FillStyle("green") context.Fill() time.Sleep(5 * time.Second) context.LineWidth(5) context.StrokeStyle("#003300") context.Stroke() }