fn change_message<C: ChangeStore>(changes: &C, change: &Hash) -> String {
            match changes.get_header(change) {
                // unwrap safe: will always be at least one line
                Ok(h) => h.message.lines().next().unwrap().to_string(),
                Err(e) => format!("[couldn't get change description: {}]", e),
            }
        }

                writeln!(w, "[{}] {}", i, dep.to_base32())?;

                writeln!(
                    w,
                    "[{}] {} # {}",
                    i,
                    dep.to_base32(),
                    change_message(changes, dep)
                )?;

                writeln!(w, "[{}]+{}", i, change.to_base32())?;

                writeln!(
                    w,
                    "[{}]+{} # {}",
                    i,
                    change.to_base32(),
                    change_message(changes, &change)
                )?;

                writeln!(w, "[*] {}", dep.to_base32())?;

                writeln!(
                    w,
                    "[*] {} # {}",
                    dep.to_base32(),
                    change_message(changes, dep)
                )?;

}
pub fn parse_comment(i: &str) -> IResult<&str, ()> {
    let (i, _) = char('#')(i)?;
    let (i, _) = take_until("\n")(i)?;
    Ok((i, ()))

        pair(space0, char('\n')),

        tuple((space0, opt(parse_comment), char('\n'))),