{"ast_node_type":"function","tokens":[{"end":56,"kind":"keyword","start":0,"text":"fn"}]}
    fn decode_attr_id(&mut self) -> rustc_span::AttrId {
impl<'a, 'tcx> SpanDecoder for DecodeContext<'a, 'tcx> {
        let sess = self.sess.expect("can't decode AttrId without Session");