anchor.diff:  ;;;; Further index operations
   
   ;;; p22
  +
   (defun range (i k)
     "Create a list containing all integers within a given range.
   If first argument is smaller than second, produce a list in decreasing order.
  
positive.code: 
  
  ;;; p27
  (defun group3 (list)
    "Group the elements of a set into disjoint subsets.
  a) In how many ways can a group of 9 people work in 3 disjoint subgroups of 2, 3 and 4 persons? 
  
negative.code:                         (1- k))))))
                          
  ;;; p24
  
  (defun lotto-select (n m)
    "Lotto: Draw N different random numbers from the set 1..M.
  The selected numbers shall be returned in a list.
  