def ladders(session, game_id):
if isinstance(game_id, str):<EOL><INDENT>game_id = lookup_game_id(game_id)<EOL><DEDENT>lobbies = get_lobbies(session, game_id)<EOL>ladder_ids = set()<EOL>for lobby in lobbies:<EOL><INDENT>ladder_ids |= set(lobby['<STR_LIT>'])<EOL><DEDENT>return list(ladder_ids)<EOL>
Get a list of ladder IDs.