self,

        mut self,

                if let Some(_iq) = stanza.try_into().ok() as Option<xmpp_parsers::iq::Iq> {}

                if let Some(iq) = stanza.try_into().ok() as Option<xmpp_parsers::iq::Iq> {
                    if let xmpp_parsers::iq::IqType::Set(element) = iq.payload {
                        if let Some(roster) =
                            element.try_into().ok() as Option<xmpp_parsers::roster::Roster>
                        {
                            self.state
                                .data
                                .roster
                                .extend(roster.items.into_iter().map(|i| (i.jid, ())));
                        }
                    }
                }