An iterator that iterates two secondary iterators in parallel

CombinedIterator.scala

class CombinedIterator[A, B](first: Iterator[A], second: Iterator[B]) extends Iterator[(Option[A], Option[B])] {
  def hasNext = first.hasNext || second.hasNext
  def next = (if (first.hasNext) Some(first.next) else None, if (second.hasNext) Some(second.next) else None)
}