pub amend: Option<String>,

    #[allow(clippy::option_option)]
    pub amend: Option<Option<String>>,

            let (h, _) = txn.hash_from_prefix(amend)?;

            let h = if let Some(ref hash) = amend {
                txn.hash_from_prefix(hash)?.0
            } else if let Some((_, (h, _))) = txn.reverse_log(&channel.borrow(), None).next() {
                h
            } else {
                return Ok(());
            };