Trying to write a function using fs2 to stream until N items have been seen

takeuntiln.scala

  def takeUntilNThings[F[_],O](n: Long, thing: O): Pipe[F,O,O] = {

      def go(s: Stream[F,O], seenCount : Int) : Pull[F,O,Unit] = {

        if(seenCount == n) {
          Pull.done
        }
        else {
          s.pull.uncons1.flatMap {

            case Some((o, tl)) =>
              
              if(o == thing) {
                Pull.output1(o) >> go(tl, seenCount + 1)
              }
              else {
                Pull.output1(0) >> go(tl, seenCount)
              }

            case None =>
              Pull.done

          }
        }
      }

      in => go(in, 0).stream

    }