anchor.diff:  
     deepSeqList = xs: y: if any (x: deepSeq x false) xs then y else y;
   
  +
     crossLists = f: foldl (fs: args: concatMap (f: map f args) fs) [f];
   
  -  # Remove duplicate elements from the list
  +
  +  # Remove duplicate elements from the list. O(n^2) complexity.
     unique = list:
       if list == [] then
         []
  
positive.code:         xs = unique (drop 1 list);
        in [x] ++ remove x xs;
  
    # Intersects list 'e' and another list
    intersectLists = e: filter (x: elem x e);
  
    # Subtracts list 'e' from another list
    subtractLists = e: filter (x: !(elem x e));
  }
  
negative.code: 
  rec {
  
    inherit (builtins) head tail length isList elemAt concatLists filter elem genList;
  
  
    # Create a list consisting of a single element.  `singleton x' is
  