SMACK/BACKEND/C++-OUT> (let ((s (constantia:ensure-indenting-stream *standard-output*)))
                         (out (:use *c++-out-dispatch-table*)
                              (:to s)
                              (:block-scope "Hello" (:%) (:block-scope "World" (:%)) (:%))))
{
  Hello
  {
    World
  }
}