pub fn seek_to_first(&mut self) -> Result<()> {
        let (blk_idx, blk_iter) = Self::seek_to_first_inner(&self.table)?;
        self.blk_idx = blk_idx;
        self.blk_iter = blk_iter;
        Ok(())
    }
Seek to the first key-value pair.
mini-lsm/src/table/iterator.rs