reporting nested forms

[Stephen J. Turnbull]

Andreas Roehler writes:

 > IMHO a routine detecting nested forms is needed - for
 > all kind of things which have a start and a end.

What is it you need that a sexp (s-expression, balanced expression)
doesn't give you?

 > Such a form should take start and end as arguments,
 > then report nesting levels and positions of beginnings
 > and ends.

Well, really it ought to take a list of start-end pairs, no?