and nt_qt () =
      let nt_unSpliced  = pack (caten (word ",@") (delayed nt_sexpr)) (fun (_,x) -> Pair(Symbol "unquote-splicing", Pair (x, Nil))) in
      let nt_unquoted  = pack (caten (char ',') (delayed nt_sexpr)) (fun (_,x) -> Pair(Symbol "unquote", Pair (x, Nil))) in
      let nt_quote  = pack (caten (char '\039') (delayed nt_sexpr)) (fun (_,x) -> Pair(Symbol "quote", Pair (x, Nil))) in
      let nt_qquote  = pack (caten (char '`') (delayed nt_sexpr)) (fun (_,x) -> Pair(Symbol "quasiquote", Pair (x, Nil))) in
      let nt_qt_res = disj_list [nt_unSpliced;nt_quote; nt_qquote; nt_unquoted] in
      nt_qt_res