def torrent_from_url(self, url, cache=True, prefetch=False):
        """Create a Torrent object from a given URL.

        If the cache option is set, check to see if we already have a Torrent
        object representing it. If prefetch is set, automatically query the
        torrent's info page to fill in the torrent object. (If prefetch is
        false, then the torrent page will be queried lazily on-demand.)

        """
        if self._use_cache(cache) and url in self._torrent_cache:
            return self._torrent_cache[url]
        torrent = Torrent(url, cache, prefetch)
        if cache:
            self._torrent_cache[url] = torrent
        return torrent
Create a Torrent object from a given URL.

        If the cache option is set, check to see if we already have a Torrent
        object representing it. If prefetch is set, automatically query the
        torrent's info page to fill in the torrent object. (If prefetch is
        false, then the torrent page will be queried lazily on-demand.)