Not sure if I got this one correctly, but it seems to me this handles the
concatenation operator; if not, I do not see why we simply add the lengths
and are done. If I'm right, maybe we should at least assert it here?
Well, I am adding the lengths but am converting the expressions
recursively. I haven't thought this through entirely but I suspect
that this function might be the best general purpose character length
calculator that we have. I might just try rolling it out into other
places that have cause trouble in the past.
Assert what, exactly?