```scala
scala> Iterator(1, 2, 3).zipWithIndex.span { case (_, idx) => idx < 1 }
res10: (Iterator[(Int, Int)], Iterator[(Int, Int)]) = (non-empty iterator,unknown-if-empty iterator)

scala> res10._1.toList
res11: List[(Int, Int)] = List((1,0))

scala> res10._2.toList
res12: List[(Int, Int)] = List((2,1), (3,2))
```