alias set=myset
myset() {
    case $2 in
        on) _v="-"; ;;
        off) _v="+"; ;;
        *) return 1; ;;
    esac
    case $1 in
        -e) \set ${_v}e; ;;
        -x) \set ${_v}x; ;;
        *) return 1; ;;
    esac
}