use libpijul::pristine::Base32;

    #[error("Cannot unrecord change {}, because change {} depends on it", change, dep.to_base32())]
    CannotUnrecord { change: String, dep: libpijul::pristine::Hash },

use std::io::Write;

use libpijul::pristine::{Base32, MutTxnT, TxnT};

use libpijul::pristine::{MutTxnT, TxnT};

        let mut stderr = std::io::stderr();
        for c in self.change_id.iter() {
            let (hash, change_id) = txn.hash_from_prefix(c)?;
            if let Some(mut channel) = txn.load_channel(channel_name) {
                let mut can_unrecord = true;

        if let Some(mut channel) = txn.load_channel(channel_name) {
            let mut changes = Vec::new();
            let channel_ = channel.borrow();
            for c in self.change_id {
                let (hash, change_id) = txn.hash_from_prefix(&c)?;
                let n = txn.get_changeset(&channel_.changes, change_id, None).unwrap();
                changes.push((hash, change_id, n, c))
            }
            std::mem::drop(channel_);
            changes.sort_by(|a, b| b.2.cmp(&a.2));
            for (hash, change_id, _, c) in changes {

                        if can_unrecord {
                            writeln!(stderr, "Cannot unrecord change {}, because the following changes depend on it:", c)?
                        }
                        can_unrecord = false;
                        writeln!(stderr, "  {}", txn.get_external(d).unwrap().to_base32())?

                        return Err((crate::Error::CannotUnrecord {
                            change: c,
                            dep: txn.get_external(d).unwrap(),
                        }).into())

                if can_unrecord {
                    txn.unrecord(&repo.changes, &mut channel, &hash)?;
                }

                txn.unrecord(&repo.changes, &mut channel, &hash)?;