def dfsInner(v: Int): Trampoline[Unit] = {
      for {
        x <- Trampoline.done(())
        _ <- Free.trampolineInstance.sequence(
          vert(v).map(x => {
            visited(v) = true
            if (!visited(x)) dfsInner(x) else Trampoline.done(())
          }).toList
        )
      } yield (scores.push(v))
    }