pub trait SstIterator {
// Required methods
fn seek_to_first(&mut self) -> Result<()>;
fn seek_to_last(&mut self) -> Result<()>;
fn seek(&mut self, key: &[u8]) -> Result<()>;
fn next(&mut self) -> Result<bool>;
fn prev(&mut self) -> Result<bool>;
fn valid(&self) -> bool;
fn key(&self) -> Option<&[u8]>;
fn value(&self) -> Option<&[u8]>;
}