class VersionedIndex {
    private NavigableMap<Key, List<VersionedRow>> versionedVals;
 
    public Cursor find(SearchRow lower, SearchRow upper, VersionInfo readVersion) {
        // Here we must first get a range of keys matching the search boundaries and then filter out the visible versions.
        // Note that versionedVals must explicitly contain deleted keys in order to be able to correctly merge results.
    }
}
 
class MergeIndex {
    public Cursor find(SearchRow lower, SearchRow upper, VersionInfo readVersion) {
        Cursor versioned = versionedIdx.find(lower, upper, readVersion);
 
        // Committed index does not need readVersion because it contains values that are 100% safe to read.
        Cursor committed = committedIdx.find(lower, upper);
 
        // Here we must return a merge cursor. In merge cursor keys from versioned cursor must override keys from committed cursor.
    }
}