let nid = url.namespace.ok_or(Error::NoKey).and_then(|ns| {
(profile.public_key == ns)
.then_some(ns)
.ok_or(Error::KeyMismatch(profile.public_key.into()))
.ok_or(Error::KeyMismatch(ns.into()))
})?;
let signer = profile.signer()?;
let mut line = String::new();