page/page.go
func (p CaptureScreenshotParams) WithClip(clip *Viewport) *CaptureScreenshotParams {
	p.Clip = clip
	return &p
}
func (p CaptureScreenshotParams) WithClip(clip *Viewport) *CaptureScreenshotParams {
	p.Clip = clip
	return &p
}
// WithClip capture the screenshot of a given region only.