anchor.diff:  
   % maps:take/2, OTP-19
   has_maps_take_2() ->
  -    code:ensure_loaded(maps),
  +    _ = code:ensure_loaded(maps),
       erlang:function_exported(maps, take, 2).
   
   test_has_maps_take_2(_Config) ->
  
positive.code: 
  % maps:iterator/1, OTP-21
  has_maps_iterator_1() ->
      code:ensure_loaded(maps),
      erlang:function_exported(maps, iterator, 1).
  
  test_has_maps_iterator_1(_Config) ->
  
negative.code: 
  % logger:add_handler/3, OTP-21
  has_logger_add_handler_3() ->
      _ = code:ensure_loaded(logger),
      erlang:function_exported(logger, add_handler, 3).
  
  test_has_logger_add_handler_3(_Config) ->
  