{"ast_node_type":"variable","tokens":[{"end":84,"kind":"keyword","start":0,"text":"let"}]}
        let mut fields: Vec<_> = (0..self.arity).map(|_| PatOrWild::Wild).collect();
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        for ipat in self.iter_fields() {