Lookup a torrent info property.

        If cache is True, check the cache first. If the cache is empty, then
        fetch torrent info before returning it.

def get(self, item, cache=None):
        """Lookup a torrent info property.

        If cache is True, check the cache first. If the cache is empty, then
        fetch torrent info before returning it.

        """
        if item not in self._keys:
            raise KeyError(item)
        if self._use_cache(cache) and (self._fetched or
                item in self._attrs):
            return self._attrs[item]
        info = self.fetch(cache=cache)
        return info[item]