page/page.go
func (p CaptureSnapshotParams) WithFormat(format CaptureSnapshotFormat) *CaptureSnapshotParams {
	p.Format = format
	return &p
}
func (p CaptureSnapshotParams) WithFormat(format CaptureSnapshotFormat) *CaptureSnapshotParams {
	p.Format = format
	return &p
}
// WithFormat format (defaults to mhtml).