// // return (start, end], not include start
func (d *DB) Iterator(start Bytes, end Bytes) (ret *Iterator) {
if len(start) == 0 {
start = nil
}
if len(end) == 0 {
end = nil
}
var iopt opt.ReadOptions
iopt.DontFillCache = true
it := d.db.NewIterator(&util.Range{Start: start, Limit: end}, &iopt)
return NewIterator(it, FORWARD)
}
