{"ast_node_type":"function","tokens":[{"end":62,"kind":"keyword","start":0,"text":"fn"}]}
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
impl<Cx: PatCx> fmt::Debug for DeconstructedPat<Cx> {
        let mut fields: Vec<_> = (0..self.arity).map(|_| PatOrWild::Wild).collect();