pub fn to_iterator_cf(
        &self,
        cf: CF,
        keys: ops::RangeToInclusive<&[u8]>,
    ) -> impl Iterator<Item = (Box<[u8]>, Box<[u8]>)> + '_ {
        let cf = self.column_family(cf);
        self.inner
            .db
            .iterator_cf(cf, IteratorMode::From(keys.end, Direction::Reverse))
            .map(Result::unwrap)
            .fuse()
        // ^ unwrap() is safe for the same reasons as in `prefix_iterator_cf()`.
    }
Iterates over key-value pairs in the specified column family `cf` in the reverse lexical
key order starting from the given `key_from`.
core/lib/storage/src/db.rs