anchor.diff:          xs = unique (drop 1 list);
         in [x] ++ remove x xs;
   
  -  # Intersects list 'e' and another list
  +
  +  # Intersects list 'e' and another list. O(nm) complexity.
     intersectLists = e: filter (x: elem x e);
   
  -  # Subtracts list 'e' from another list
  +
  +  # Subtracts list 'e' from another list. O(nm) complexity.
     subtractLists = e: filter (x: !(elem x e));
  +
   }
  
positive.code: 
    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
    unique = list:
      if list == [] then
        []
  
negative.code: 
  
    # Return a list of integers from `first' up to and including `last'.
    range =
      if builtins ? genList then
        first: last:
          if first > last
          then []
          else genList (n: first + n) (last - first + 1)
      else
        first: last:
          if last < first
          then []
          else [first] ++ range (first + 1) last;
  
  
    # Partition the elements of a list in two lists, `right' and
  