anchor.diff:        (let ((result (make-instance 'class-name
   		      :form (car body))))
   	(if (and (not (null (cdr body)))
  -		 (symbol-equal (cadr body) #:into))
  +		 (symbol-equal (cadr body) '#:into))
   	    (cond ((null (cddr body))
   		   (error 'expected-simple-var-but-end))
   		  ((not (symbolp (caddr body)))
  
positive.code:   (parse-alternative body
  		     #'parse-with-clause
  		     #'parse-initial-final
  		     #'parse-for/as-clause)
  
  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  ;;;
  
negative.code:   `(defun ,name (,body-var)
       (when (or (null ,body-var)
  	       (and ,@(mapcar (lambda (start-symbol)
  				`(not (symbol-equal (car ,body-var) ',start-symbol)))
  			      start-symbols)))
         (return-from ,name (values nil ,body-var)))
       ,@body))
  