aabb_helpers.rb:19: warning: `&' interpreted as argument prefix

There are several warnings using &

not sure if you want to fix, or keep it. I guess it depends on your style.

The fix would be to change:

@root.each_leaf &blk

to

@root.each_leaf(&blk)

I've seen other ruby guys use the same though, they dont like the ()
so perhaps the real fix is to ask ruby core to change this warning
hehehehe.