anchor.diff:  (defun request-parser-url (header-info)
     (header-info-path header-info))
   (defun request-parser-headers (header-info)
  -  (header-info-headers header-info))+  (header-info-headers header-info))
  
positive.code:          'base-char 'character))
  
  (deftype ascii-simple-string ()
    '(simple-array ascii-char))
  
  ;;;;;;;;;;;;;;;;;;;;;;;;;;
  ;;;; parser stages support
  
negative.code: 
  (declaim (ftype (function (list string-designator) (or null simple-string)) request-header))
  (defun request-header (header-info-headers header)
    (let ((match (find (string header) header-info-headers
                       :key #'car
                       :test (lambda (a b)
                               (declare (type ascii-simple-string a b))
                               (string= a b)))))
      (when match (cdr match))))
  
  ;; methods for http.lisp
  