{"ast_node_type":"variable","tokens":[{"end":48,"kind":"keyword","start":0,"text":"let"}]}
        let itctx = ImplTraitContext::Universal;
        let header = self.lower_fn_header(sig.header, hir::Safety::Safe, attrs);
        let (generics, decl) = self.lower_generics(generics, id, itctx, |this| {