func (r InterfaceMap) AppendSysResourceIfExists(sr string, sys *system.System) (*Interface, system.Interface, bool) {
    sysres := sys.NewInterface(sr, sys, util.Config{})
    // FIXME: Do we want to be silent about errors?
    res, _ := NewInterface(sysres, util.Config{})
    if e, _ := sysres.Exists(); e != true {