iterator.go
func (it *Iterator) Next() {
	next := it.list.getNext(it.nd, 0)
	it.setNode(next, false)
}
func (it *Iterator) Next() {
	next := it.list.getNext(it.nd, 0)
	it.setNode(next, false)
}
func ( it * Iterator ) Next ( ) { next := it . list . getNext ( it . nd , 0 ) it . setNode ( next , false ) }
// Next advances to the next position. If there are no following nodes, then
// Valid() will be false after this call.
Next advances to the next position . If there are no following nodes then Valid () will be false after this call .