A[] = key

Test(M) =
   public.M = $M
   A.foreach(key) =>
      M = $(M.add $(key), new)
      export M

   new = $(M.find key)
   if $(equal $(new), new)
      println($"export M worked [SUCCESS]")
   else
      eprintln($"export M had no effect [FAILURE]")
      exit 1

X. =
   extends $(Map)
   $|key| = old

Test($X)
