local allowed, err_type, err_condition = self:can_set_role(actor, occupant_jid, role);
if not allowed then return allowed, err_type, err_condition; end
local occupant = self._occupants[occupant_jid];
local allowed, err_type, err_condition = self:can_set_role(actor, occupant_jid, role);
if not allowed then return allowed, err_type, err_condition; end
local occupant = self._occupants[occupant_jid];