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