pub trait QueryExt<'d> {
fn search_threads<'q, Q: Into<Supercow<'q, Query<'d>>>>(
query: Q
) -> Result<Threads<'q, Query<'d>>, Error> { ... }
fn search_messages<'q, Q: Into<Supercow<'q, Query<'d>>>>(
query: Q
) -> Result<Messages<'q, Query<'d>>, Error> { ... }
}