{"ast_node_type":"variable","tokens":[{"end":90,"kind":"keyword","start":0,"text":"let"}]}
        let ret = unsafe { libc::write(libc::STDERR_FILENO, s.as_ptr().cast(), s.len()) };
    fn write_str(&mut self, s: &str) -> Result<(), fmt::Error> {
        if ret == -1 { Err(fmt::Error) } else { Ok(()) }