{"ast_node_type":"variable","tokens":[{"end":27,"kind":"keyword","start":0,"text":"let"}]}
    let var = var.as_str();
fn lookup_env<'cx>(cx: &'cx ExtCtxt<'_>, var: Symbol) -> Result<Symbol, VarError> {
    if let Some(value) = cx.sess.opts.logical_env.get(var) {