anchor.diff:  
       %% literally #{ "hi" => "value", a=>33, b=>55 } in the internal order
       #{ a:=33, b:=55, "hi" := "value"} = erlang:binary_to_term(<<131,116,0,0,0,3,
  -	107,0,2,104,105, % "hi" :: list()
  +	107,0,2,104,105,            % "hi" :: list()
   	107,0,5,118,97,108,117,101, % "value" :: list()
  -	100,0,1,97, % a :: atom()
  -	97,33, % 33 :: integer()
  -	100,0,1,98, % b :: atom()
  -	97,55  % 55 :: integer()
  +	100,0,1,97,                 % a :: atom()
  +	97,33,                      % 33 :: integer()
  +	100,0,1,98,                 % b :: atom()
  +	97,55                       % 55 :: integer()
   	>>),
   
   
  
positive.code:     {'EXIT',{badarg,[{maps,put,_,_}|_]}} = (catch maps:put(1,a,atom)),
      {'EXIT',{badarg,[{maps,put,_,_}|_]}} = (catch maps:put(1,a,[])),
      {'EXIT',{badarg,[{maps,put,_,_}|_]}} = (catch maps:put(1,a,<<>>)),
       ok.
  
  t_bif_map_remove(Config) when is_list(Config) ->
      0  = erlang:map_size(maps:remove(some_key, #{})),
  
negative.code: 
      M1 = #{ "hi" := "hello"} = maps:put("hi", "hello", #{}),
  
      true = is_members(["hi"],maps:keys(M1)),
      true = is_members(["hello"],maps:values(M1)),
  
      M2 = #{ int := 3 } = maps:put(int, 3, M1),
  
      true = is_members([int,"hi"],maps:keys(M2)),
      true = is_members([3,"hello"],maps:values(M2)),
  
      M3 = #{ <<"key">> := <<"value">> } = maps:put(<<"key">>, <<"value">>, M2),
  
      true = is_members([int,"hi",<<"key">>],maps:keys(M3)),
      true = is_members([3,"hello",<<"value">>],maps:values(M3)),
  
      M4 = #{ 18446744073709551629 := wat } = maps:put(18446744073709551629, wat, M3),
  
      true = is_members([18446744073709551629,int,"hi",<<"key">>],maps:keys(M4)),
      true = is_members([wat,3,"hello",<<"value">>],maps:values(M4)),
  
      M0 = #{ 4 := number } = M5 = maps:put(4, number, M4),
  
      true = is_members([4,18446744073709551629,int,"hi",<<"key">>],maps:keys(M5)),
      true = is_members([number,wat,3,"hello",<<"value">>],maps:values(M5)),
  
      M6 = #{ <<"key">> := <<"other value">> } = maps:put(<<"key">>, <<"other value">>, M5),
  
      true = is_members([4,18446744073709551629,int,"hi",<<"key">>],maps:keys(M6)),
      true = is_members([number,wat,3,"hello",<<"other value">>],maps:values(M6)),
  
      %% error case
      {'EXIT',{badarg,[{maps,put,_,_}|_]}} = (catch maps:put(1,a,1 bsl 65 + 3)),
  