{"ast_node_type":"other","tokens":[{"end":11,"kind":"keyword","start":0,"text":"///"}]}
    /// ```
    /// Const = "const" ($ident | "_") Generics ":" $ty (= $expr)? WhereClause ";" ;
    fn parse_const_item(&mut self) -> PResult<'a, (Ident, Generics, P<Ty>, Option<P<ast::Expr>>)> {