anchor.diff:         (:div
           (if cluster
               (append (list (internal-buffers-markup)) 
  -                    (loop for cluster in (alex:hash-table-values (cluster-buffers))
  -                          collect (cluster-markup cluster)))
  +                    (loop for cluster-key being the hash-key
  +                          using (hash-value cluster) of (cluster-buffers)
  +                          collect (cluster-markup cluster-key cluster)))
               (loop for buffer in (buffer-list)
                     collect (buffer-markup buffer))))))))
  
positive.code:                                           :string-contents (document-get-paragraph-contents)))))
                 (analysis::tf-idf-vectorize-documents collection)
                 (analysis::generate-document-distance-vectors collection)
                 (analysis::dbscan collection :minimum-points 3 :epsilon 0.10)
                 (analysis::clusters collection)))
             (buffer-markup (buffer)
               "Create the presentation for a buffer."
  
negative.code:                   (:a :class "button"
                        :href (lisp-url `(nyxt::switch-buffer :id ,(id buffer))) "→")
                    (:span (title buffer) " - "(quri:render-uri (url buffer))))))
             (cluster-markup (cluster-id cluster)
               "Create the presentation for a cluster."
               (markup:markup
                (:div (:h2 (format nil "Cluster ~a" cluster-id))
                      (loop for document in cluster
                            collect (buffer-markup (analysis::source document))))))
             (internal-buffers-markup ()
  