{"ast_node_type":"variable","tokens":[{"end":51,"kind":"keyword","start":0,"text":"let"}]}
                let span = self.lower_span(t.span);
                let kind = hir::TyKind::Ref(lifetime, self.lower_mt(mt, itctx));
                let arg = hir::Ty { kind, span, hir_id: self.next_id() };