anchor.diff:     (term-infos)
      (freq-stream)
      (prox-stream)
  -   (norms)
  +   (norms :initform (make-hash-table :test #'equal))
      (norms-dirty-p)
      (tv-reader-orig))
   )
  
positive.code: 	       (file-exists-p directory (add-file-extension segment "del")))
        (delete-file directory (add-file-extension segment "del")))
      (when norms-dirty-p
        (dosequence (norm norms)
  	(when (dirty-p norm)
  	  (re-write norm directory segment (max-doc self) cfs-reader))))
      (setf deleted-docs-dirty-p NIL
  	  norms-dirty-p NIL
  	  undelete-all-p NIL)))
  
negative.code: 	(setf deleted-docs (read-bit-vector directory (add-file-extension segment "del"))))
        (setf freq-stream (open-segment-file dir segment "frq" :input))
        (setf prox-stream (open-segment-file dir segment "prx" :input))
        (setf norms-dirty-p NIL)
        (open-norms self dir)
        (setf tv-reader-orig NIL)
  