Ensure that given function names remain in :PROGRAM mode.
(ensure-program-only-flag my-fn your-fn)
(ensure-program-only-flag fn1 fn2 ... fnk)
where each fni is a literal symbol which should have a program
mode definition. Each fni not already flagged as "program only" is
flagged as such. This prevents it from being migrated to logic mode
or being used in a macro.
This is a pseudo-event, meaning it can be used in an event context but does
not (ever) change the world.
Note that the normal undoing mechanism (see ubt) does not undo the effects
of this pseudo-event.