anchor.diff:  
   json_encode_string_utf8_1([C | Cs]) when C >= 0, C =< 16#7f ->
       NewC = case C of
  +               $\\ -> "\\\\";
                  _ when C >= $\s, C < 16#7f -> C;
  -               $\\ -> "\\\\";
                  $\t -> "\\t";
                  $\n -> "\\n";
                  $\r -> "\\r";
  
positive.code:     {"", "\"\""},
      {[], "\"\""},
      {"\n\n\n", "\"\\n\\n\\n\""},
      {obj_new(), "{}"},
      {obj_from_list([{"foo", "bar"}]), "{\"foo\":\"bar\"}"},
      {obj_from_list([{"foo", "bar"}, {"baz", 123}]),
  
negative.code: 
  json_encode_string_unicode_1([C | Cs]) ->
      NewC = case C of
                 $\\ -> "\\\\";
                 _ when C >= $\s, C < 16#7f -> C;
                 $\t -> "\\t";
                 $\n -> "\\n";
                 $\r -> "\\r";
  