{"ast_node_type":"variable","tokens":[{"end":89,"kind":"keyword","start":0,"text":"let"}]}
                let generic_params = self.lower_lifetime_binder(t.id, &f.generic_params);
            TyKind::FnPtr(f) => {
                hir::TyKind::FnPtr(self.arena.alloc(hir::FnPtrTy {