'Adds a track or directory to the playlist, specified by the
path. If `send_id`, write each item\'s id to the client.'

def _add(self, path, send_id=False):

    for item in self._all_items(self._resolve_path(path)):
        self.playlist.append(item)
        if send_id:
            (yield (u'Id:    ' + six.text_type(item.id)))
    self.playlist_version += 1
