let s: libpijul::Merkle = s.into();

                let (a, b) = if s == libpijul::Merkle::zero() {
                    (None, None)
                } else {
                    (Some(a), Some(b))
                };

    from: u64,

    from: Option<u64>,

    for x in libpijul::pristine::changeid_log(txn, chan, from.into())? {

    let f = if let Some(f) = from {
        (f + 1).into()
    } else {
        0u64.into()
    };
    for x in libpijul::pristine::changeid_log(txn, chan, f)? {

        if n <= from {
            continue;
        }

    let mut a_was_found = false;

            a_was_found = true;

    Ok((aa, a, state))

    if a_was_found {
        Ok((aa, a, state))
    } else {
        Ok((0, 0, Merkle::zero().into()))
    }