func (itr *blockIterator) SeekToLast() {
	itr.err = nil
	for itr.Init(); itr.Valid(); itr.Next() {
	}
	itr.Prev()
}
func (itr *blockIterator) SeekToLast() {
	itr.err = nil
	for itr.Init(); itr.Valid(); itr.Next() {
	}
	itr.Prev()
}
// SeekToLast brings us to the last element. Valid should return true.