var d = new D(false, 'b', 123.123, 2345, "new line ->\n<-", null, 1111, "\t\f\"\r\\/")
d.d = d
-for o in new Array[nullable Serializable].with_items(a, b, c, d) do
+for o in new Array[Serializable].with_items(a, b, c, d) do
var stream = new StringOStream
var serializer = new JsonSerializer(stream)
serializer.serialize(o)