static F0<AutoCloseable> dm_rEnter(DynModule mod default dm_current()) {
  ret mod == null ? null : func -> AutoCloseable { mod.enter() };
}

static Runnable dm_rEnter(DynModule mod default dm_current(), Runnable r) {
  ret mod == null || r == null ? r : r { temp mod.enter(); r.run(); };
}