anchor.diff:    (let* ((begin-index (add-state nil '∈))
            (end-index   (add-state nil '∈))
            (len         (string-length union-string))
  -         (split-cons  (split-cons (split-union union-string)))
  +         (split-cons (split-union union-string))
            (regex1 (car split-cons))
            (regex2 (cdr split-cons)))
       (let* ((ret-parse    (parse-regex regex1))
  
positive.code:               ((eq #\( current-char)
                 (let* ((rest-exp (subseq regex-string index))
                        (paren-exp (get-first-paren rest-exp))
                        (parse-ret nil))
                   (if (is-union paren-exp)
                     (if (not (union-ugly-p paren-exp))
                       ()))
                   (set-begin-end-f (get-ret 'begin parse-ret)
                                    (get-ret 'end   parse-ret))
                   (incf index (1- (get-ret 'len parse-ret)))))
                (t (progn
                     ; Simple State
                     (let ((s-index (add-state current-char nil)))
  
negative.code:            (end2-index   (get-ret 'end   ret-parse)))
        (setf (state-out2 (aref trans-table begin-index)) begin2-index)
        (setf (state-out1 (aref trans-table end2-index)) end-index))
      (list begin-index end-index (+ 2 len))))
  
  
  (defun get-first-paren (regex-string)
  