markOutput :: Monad m => Ref -> BuilderT g m ()
markOutput !ref = do
    bs_circ . circ_outputs %= flip V.snoc ref
    bumpRefCount ref
markOutput :: Monad m => Ref -> BuilderT g m ()
markOutput !ref = do
    bs_circ . circ_outputs %= flip V.snoc ref
    bumpRefCount ref
markOutput !ref = do
    bs_circ . circ_outputs %= flip V.snoc ref
    bumpRefCount ref