Ah, ok - I misinterpreted the article.

Actually, the article seems to be wrong? It seems to imply that this shouldn't work:

    Io> x := Object clone do( forward := 0; a := 1 )
    ==>  Object_0x1003a2e90:
      a                = 1
      forward          = 0

    Io> x a
    ==> 1
    Io> x b
    ==> 0
    Io> x b := 2
    ==> 2
    Io> x b
    ==> 2

(paragraph: There are some things you should know about forward(). It's very powerful. Too powerful. [...])