Le Tue, Nov 15, 2005 at 10:51:30AM +1030, Will Robertson:
> So we get ... (other "1") (cseq "\previouslet") (cseq "\test")
> and end up with the equivalent of \let\test=1 .
> Ohhh, but I think I get it now. This is no more useful than actually  
> looking at nodes, since anything that survives to be \previouslet  
> will be turned into a node anyway.

Yes. It's more clearly seen with:


What is \test? The right brace? The box? The box is not a token any
more. So we have to keep on that:
- look ahead for tokens
- look backward for nodes.