iterator.go
func (it *Iterator) Close() {
	it.snap.Close()
	it.snap.db.store.FreeBuf(it.buf)
	it.iter.Close()
}
func (it *Iterator) Close() {
	it.snap.Close()
	it.snap.db.store.FreeBuf(it.buf)
	it.iter.Close()
}
// Close executes destructor for iterator