You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: primitive_types6.rs
    path of file: ./repos/rust-course/assets/rustlings-zh/exercises/primitive_types
    
    the code of the file until where you have to start completion: // primitive_types6.rs
// 使用元组索引（tuple index）来访问 `numbers` 的第二个元素。
// 你可以把第二
    
fn indexing_tuple() {
    let numbers = (1, 2, 3);
    // 用元组索引的语法替换下面的 ???
    let second = ???;

    assert_eq!(2, second,
        "This is not the 2nd number in the tuple!")// 译：这不是元组中的第二个数字!
}