anchor.diff:  (defclass tag-index (index) ())
   
   (defmethod discover ((doc-type (eql (find-class 'tag-index))))
  +  (setf *all-tags* (all-tags))
     (let ((content (by-date (find-all 'post))))
       (dolist (tag (all-tags))
         (add-document (index-by-tag tag content)))))
  
positive.code:    (content :initarg :content :reader index-content)))
  
  (defmethod render ((object index) &key prev next)
    (funcall (theme-fn 'index) (list :tags (all-tags)
                                     :months (all-months)
                                     :config *config*
                                     :index object
                                     :prev prev
  
negative.code: (in-package :coleslaw)
  
  (defvar *all-months* nil
    "The list of months in which content was authored.")
  (defvar *all-tags* nil
    "The list of tags which content has been tagged with.")
  
  (defclass index ()
    ((slug :initarg :slug :reader index-slug)
  