def METHOD_NAME(self, link):
    """Setter to be used as a Qt slot.
    Saves old shown URL in self._old_url and restores it later if a link is
    "un-hovered" when it gets called with empty parameters.
    Args:
        link: The link which was hovered (string)
    """
    if link:
        qurl = QUrl(link)
        if qurl.isValid():
            self._hover_url = urlutils.safe_display_string(qurl)
        else:
            self._hover_url = '(invalid URL!) {}'.format(link)
    else:
        self._hover_url = None
    self._update_url()