{"ast_node_type":"function","tokens":[{"end":80,"kind":"keyword","start":0,"text":"fn"}]}
    fn check_duplicate<S: Stage>(&self, cx: &AcceptContext<'_, '_, S>) -> bool {
    /// Checks, and emits an error when a stability (or unstability) was already set, which would be a duplicate.
        if let Some((_, _)) = self.stability {