{"ast_node_type":"function","tokens":[{"end":60,"kind":"keyword","start":0,"text":"fn"}]}
    fn from_pattern(pat: &'p DeconstructedPat<Cx>) -> Self {
impl<'p, Cx: PatCx> PatStack<'p, Cx> {
        PatStack { pats: smallvec![PatOrWild::Pat(pat)], relevant: true }