anchor.diff:  
   (defmethod purge ((agent agent))
     "Purge emphemeral materials from the agent."
  -  (setf (current-link agent) nil)
  +  (setf (current-url agent) nil)
     (setf (errors agent) '())
     (setf (content agent) nil)
     (setf (code agent) nil)
  
positive.code: 		    (or
  		     (not (> (length x) 0)) ; bigger than 0
  		     (cl-ppcre::scan "^#" x) ; not a JS hash trick
  		     (cl-ppcre::scan "^ftp\:\/\/" x))) ; not ftp
  		  (PURI:URI-PARSE-ERROR (upe) (declare (ignore upe)) t)))
  	     list))
  
  
negative.code: 		 ((search "png" (cdr (assoc :CONTENT-TYPE headers))) "")
  		 ((search "gif" (cdr (assoc :CONTENT-TYPE headers))) "")
  		 ((search "pdf" (cdr (assoc :CONTENT-TYPE headers))) "")
  		 ;; TODO: Or, for that matter, tarballs.
  		 ((search "tgz" (cdr (assoc :CONTENT-TYPE headers))) "")
  		 ((search "bz2" (cdr (assoc :CONTENT-TYPE headers))) "")
  		 ((search "zip" (cdr (assoc :CONTENT-TYPE headers))) "")
  		 ((search "gzip" (cdr (assoc :CONTENT-TYPE headers))) "")
  		 ((search "gz" (cdr (assoc :CONTENT-TYPE headers))) "")
  		 (t (fill-with-content ,agent body)))
  	       (setf (code ,agent) response-code)
  	       ;; Return if we made it without an error.
  