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: kodenook.rs
    path of file: ./repos/roadmap-retos-programacion/Roadmap/00 - SINTAXIS, VARIABLES, TIPOS DE DATOS Y HOLA MUNDO/rust
    
    the code of the file until where you have to start completion: 
// https://www.rust-lang.org

/*
    Comments
*/

// single-line comment

/*
    this is a
    multi-line comment
*/


/// This Rust program declares variables of different types and prints a greeting message.
fn main(){

    /*
        Vars a
    
fn main(){

    /*
        Vars and Constants
    */

    // The variables that start with _ are not used

    let _x = "4"; // variable inmutable
    let mut _y = "5"; // variable mutable
    const _Z: &str = "6"; // const must have the type

    /*
        Primitive Types
    */

    let _number: u8 = 16; // unsigned 8-bits number, i8 for signed, there are 8, 16, 32, 64 and 128 bits
    let _boolean: bool = true;
    let _floating32: f32 = 2.5;
    let _floating64: f64 = 2.553;
    let _letter: char = 'a';

    println!("Â¡Hello, Rust!");
}