anchor.diff:      whatever.
   
   test_map(Malt) ->
  -    [2,4,6,8,10] = plists:map(fun (X) -> 2*X end, [1,2,3,4,5], Malt).
  +    [2,4,6,8,10] = plists:map(fun (X) -> 2*X end, [1,2,3,4,5], Malt),
  +    % edge cases
  +    [2] = plists:map(fun (X) -> 2*X end, [1], Malt),
  +    [] = plists:map(fun (X) -> 2*X end, [], Malt).
   
   test_partition(Malt) ->
       {[2,4,6],[1,3,5]} = plists:partition(fun even/1, [1,2,3,4,5,6], Malt).
  
positive.code: 		  A =< B
  	  end,
      [1,2,2,3,4,5,5] = plists:sort(Fun, [2,4,5,1,2,5,3], Malt),
      [1,2,2,3,4,5,5] = plists:sort(Fun, [2,4,5,1,2,5,3], Malt).
  
  test_usort(Malt) ->
      Fun = fun (A, B) ->
  
negative.code:     true = plists:all(fun even/1, [2,4,6,8], Malt),
      false = plists:all(fun even/1, [2,4,5,8], Malt).
  
  even(X) when X rem 2 =:= 0 ->
      true;
  even(_) ->
      false.
  
  test_any(Malt) ->
      true = plists:any(fun even/1, [1,2,3,4,5], Malt),
  