anchor.diff:  (defpackage #:yacc
     (:use #:common-lisp)
     (:export #:make-production #:make-grammar #:make-parser #:parse-with-lexer
  -           #:define-grammar #:define-parser
  +           #:define-grammar #:define-parser #:yacc-eof-symbol
              #:yacc-parse-error #:yacc-parse-error-terminal
              #:yacc-parse-error-value #:yacc-parse-error-expected-terminals)
     #+CMU
  
positive.code:                  (cond
                     ((and (eq 's-prime (item-symbol item))
                           (= 1 (item-position item)))
                      (when (member 'eof la)
                        (set-action k (list 'eof)
                                    (make-accept-action)
                                    (item-production item))))
                     (t
  
negative.code: (defun compute-all-lookaheads (kernels grammar)
    "Compute the LR(1) lookaheads for all the collections in KERNELS."
    (declare (list kernels) (type grammar grammar))
    (setf (item-lookaheads (kernel-item (car kernels))) (list 'yacc-eof-symbol))
    (let ((previously-changed kernels) (changed '())
          (propagate-only nil))
      (declare (optimize (speed 3) (space 0)))
  