{"ast_node_type":"variable","tokens":[{"end":84,"kind":"keyword","start":0,"text":"let"}]}
    let source_file = ast::SourceFile::parse(input, Edition::CURRENT).ok().unwrap();
fn check_enable_hints(input: &str, opts: &CfgOptions, expected_hints: &[&str]) {
    let tt = source_file.syntax().descendants().find_map(ast::TokenTree::cast).unwrap();