code: func split(head *llNode) (left, right *llNode) {
  	left = head
  	if head == nil || head.next == nil {
  		return
  	}
  	right = head
  	sprinter := head
  	prev := head
  	for sprinter != nil && sprinter.next != nil {
  		prev = right
  		right = right.next
  		sprinter = sprinter.next.next
  	}
  	prev.next = nil
  	return
  }
docs: // split breaks a list in half.