undefined toString??

One of the things that it has always made me laugh on the new Flash AS2 is the translation of the undefined value (mmhh.. not a value, it’s undefined!).

a = undefined;trace(a.toString()) // undefined

b = a + " is not a string"trace(b) // "undefined is not a string"

Probably I don’t yet understand the strict data typing concept (quite sure), but undefined CAN’T be converted to "undefined".
It’s so Stupid for me!