Thu Aug 16 09:01:41 EDT 2018

Debug probes

Is it enough to use the environment-based probing?

At the bottom level, probes are just ignored if they are not defined.
At the top level, probes can be pulled out if they are defined, and
raise an error if they are not.  This seems better altoghether.

Maybe a combination of both will do?  Use the first probe mechanism to
collect names into the meta level, then use the former environment
mechanism to teleport signals.