code: func SeparatorNew(orientation Orientation) (*Separator, error) {
  	c := C.gtk_separator_new(C.GtkOrientation(orientation))
  	if c == nil {
  		return nil, nilPtrErr
  	}
  	return wrapSeparator(glib.Take(unsafe.Pointer(c))), nil
  }
docs: // SeparatorNew is a wrapper around gtk_separator_new().