$ mzscheme
  Welcome to Racket v5.2.1.
  > (load "as.scm")
  Use (quit) to quit, (tl) to return here after an interrupt.
  arc> ^Cuser break
  > (acompile "arc.arc")
  [...output elided...]
  > (exit)
  $ head arc.arc.scm
  (begin
    (let ((zz
           (ar-funcall2
            _annotate
            'mac
            (let ((| do| (lambda args `((fn () ,@(ar-nil-terminate args))))))
              | do|))))
      (namespace-set-variable-value! '_do zz)
      zz))