What we do instead is to add methods to the rules,
which get added to the appropriate nodes, to build
the data structure we want - *after* Treetop has worked
its magic - and then the Treetop tree can be gc'd.

Make these methods recursive, so you can just call e.g.
"value" on the top node, and it builds the whole structure
you need. Don't try to write code to walk the syntax tree
from the outside, as some newbies have tried.

Clifford Heath.