code: def muc_set_affiliation(self, jid, affiliation, *, reason=None):
          
          return (yield from self.service.set_affiliation(
              self._mucjid,
              jid, affiliation,
              reason=reason))
docs: Convenience wrapper around :meth:`.MUCClient.set_affiliation`. See
          there for details, and consider its `mucjid` argument to be set to
          :attr:`mucjid`.