{"ast_node_type":"variable","tokens":[{"end":72,"kind":"keyword","start":0,"text":"let"}]}
        let ret = unsafe { libc::fcntl(file.as_raw_fd(), cmd, &flock) };
        let cmd = if wait { libc::F_SETLKW } else { libc::F_SETLK };
        if ret == -1 { Err(io::Error::last_os_error()) } else { Ok(Lock { file }) }