These will provide additional language features that are implemented in
terms of the basic zcl functionality, so that applications can opt-in to
some more-dynamic behavior if desired.
The general pattern here will be to provide a function that
partially-decodes a given zcl.Body to look for certain block types and
then returns its result along with a zcl.Body representing the remaining,
as-yet-unprocessed content.
Martin Atkins