[_ap,[_ap,[a],[b]],[c]] [_ap,-(a)(b),(c)] --(a)(b)(c) read:(aaa (bbb (ccc)) (ddd))
 (_ctx (_seq (qt (xxx)) (kkk)) (stk) (env)) = (_ctx (kkk) (_push (xxx) (stk)) (env))
 (_ctx (kkk) (_push (xxx) (stk)) (env))
 (_ctx (kkk) (_push (xxx) (stk)) (env))
 (_trans (_sym (_ctx (_seq (qt (xxx)) (kkk)) (stk) (env))) (_ctx (_seq (qt (xxx)) (kkk)) (stk) (env)))
 (_ctx (kkk) (_push (xxx) (stk)) (env)) = (_ctx (kkk) (_push (xxx) (stk)) (env))