mergeSorted for the same type of Process

merge.scala

def mergeSorted[F[_], I, A: Order](sourceLeft: Process[F, I], sourceRight: Process[F, I])(f: I => A): Process[F, I] = {
  mergeSorted(sourceLeft, f)(sourceRight, f).flatMap {
    case Both(a, b) => Process.emit(a) ++ Process.emit(b)
    case This(a) => Process.emit(a)
    case That(b) => Process.emit(b)
  }
}