{"ast_node_type":"function","tokens":[{"end":95,"kind":"keyword","start":0,"text":"let"}]}
            let after = ast_mut_from_text::<ast::LetStmt>(&format!("fn f() {{ {expected} }}"));
            assert_eq!(let_stmt.to_string(), after.to_string(), "{let_stmt:#?}\n!=\n{after:#?}");