You do not need to implement comma or backquote, despite what the
original spec says.  (I will take it out of the spec as soon as I get a
chance.)  If you have already implemented it, hopefully you realized that
it's just two lines of code ;).

But feel free not to mention it in your design doc or implementation!
New spec coming soon!  Sorry about this.. my mistake.

UPDATE: The spec has been updated.  You can pull down a new copy of the
pdf if it makes you feel better.  The lexer has also been programmed to
ignore backquote and comma, so you can either feel free to grab a new
copy of it, or just leave your current one.  We won't test your code for
comma or backquote, so you can ignore those symbols.

-Thomas