anchor.diff:      :collect (loop
                  :for index :from 0 :below card
                  :for item :in set
  -               :nconc (if (logbitp index indicator) (list item) nil) 
  -               :into result 
  +               :nconc (if (logbitp index indicator) (list item) nil)
  +               :into result
                  :finally (return result)) :into result
       :finally (return result)))
   
  
positive.code:   (:documentation
     "
  This package exports list processing functions.
      
  
  License:
  
      AGPL3
      
      Copyright Pascal J. Bourguignon 2003 - 2014
      
      This program is free software: you can redistribute it and/or modify
      it under the terms of the GNU Affero General Public License as published by
      the Free Software Foundation, either version 3 of the License, or
      (at your option) any later version.
      
      This program is distributed in the hope that it will be useful,
      but WITHOUT ANY WARRANTY; without even the implied warranty of
      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      GNU Affero General Public License for more details.
      
      You should have received a copy of the GNU Affero General Public License
      along with this program.
      If not, see <http://www.gnu.org/licenses/>
  
negative.code:                 (NSPLIT-LIST (LIST 'A 'B 'C) 1) --> (A) ; (B C)
                  (NSPLIT-LIST (LIST 'A 'B 'C) 2) --> (A B) ; (C)
                  (NSPLIT-LIST (LIST 'A 'B 'C) 3) --> (A B C) ; NIL
  POSITION:       POSITION OF THE SPLIT;
                  WHEN FROM-START AND 0<=POSITION<=(LENGTH LIST),
                  THAT'S THE LENGTH OF THE FIRST RESULT
  FROM-START:     THE DEFAULT, SPLIT COUNTING FROM THE START.
  