{"ast_node_type":"other","tokens":[{"end":44,"kind":"keyword","start":0,"text":"///"}]}
    /// the attribute represented by `Attr`.
    /// Note that the returned syntax node might be a `#[cfg_attr]`, or a doc comment, instead of
    pub fn source_of(&self, attr: &Attr) -> InFile<&Either<ast::Attr, ast::Comment>> {