Example. consider a procedure that spawns an actor and then returns
some value relevant to communicating to that actor:
(define (spawn-an-actor)
(define name (gensym))
(spawn
(on (asserted (... name ...))
...)
...)
name)
And the module top level tries to boot and use this actor with a define:
(define the-name (spawn-an-actor))
(spawn ... use the-name ...)
The new module-begin analyzes (forms that expand to) define-values to
wrap the body with a capture-actor-actions, allowing such spawns to be
detected.