{"ast_node_type":"variable","tokens":[{"end":55,"kind":"keyword","start":0,"text":"let"}]}
        let mut expected_str = DiagStyledString::new();
    fn add_to_diag<G: EmissionGuarantee>(self, diag: &mut Diag<'_, G>) {
        expected_str.push(self.expected.fn_sig(self.tcx).to_string(), false);