pub trait Sealed {} impl Sealed for git_ref::Reference {} /// Extensions for [references][git_ref::Reference].pub trait ReferenceExt {    /// Attach [`Repository`][crate::Repository] to the given reference. It can be detached later with [`detach()]`.    fn attach(self, repo: &crate::Repository) -> crate::Reference<'_>;} impl ReferenceExt for git_ref::Reference {    fn attach(self, repo: &crate::Repository) -> crate::Reference<'_> {        crate::Reference::from_ref(self, repo)    }}