@xmpp.iq('{jabber:iq:roster}query')
    def roster(self, iq):
        """A roster is this account's list of contacts; it may be
        fetched or updated."""

        roster = self.rosters.get(self)
        method = getattr(self, iq.get('type') % '%s_roster')
        return method and method(iq, roster)
dataset/ETHPy150Open HenryHu/pybbs/xmppserver.py/XMPPServer.roster/swapped operands of `%`