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: lib.rs
    path of file: ./repos/CYFS/src/3rd/cyfs-sha2/src
    
    the code of the file until where you have to start completion: //! An implementation of the [SHA-2][1] cryptographic hash algorithms.
//!
//! There are 6 standard algorithms specified in the SHA-2 standard:
//!
//! * `Sha224`, which is the 32-bit `Sha256` algorithm with the result truncated
//! to 224 bits.
//! * `Sha256`, which is the 32-bit `Sha256` algorithm.
//! * `Sha384`, which is the 64-bit `Sha512` algorithm with the result truncated
//! to 384 bits.
//! * `Sha512`, which is the 64-bit `Sha512` algorithm.
//! * `Sha512Trunc224`, which is the 64
    
//! # fn main() {
//! use sha2::{Sha256, Sha512, Digest};
//!
//! // create a Sha256 object
//! let mut hasher = Sha256::new();
//!
//! // write input message
//! hasher.input(b"hello world");
//!
//! // read hash digest and consume hasher
//! let result = hasher.result();
//!
//! assert_eq!(result[..], hex!("
//!     b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9
//! ")[..]);
//!
//! // same for Sha512
//! let mut hasher = Sha512::new();
//! hasher.input(b"hello world");
//! let result = hasher.result();
//!
//! assert_eq!(result[..], hex!("
//!     309ecc489c12d6eb4cc40f50c902f2b4d0ed77ee511a7c7a9bcd3ca86d4cd86f
//!     989dd35bc5ff499670da34255b45b0cfd830e81f605dcf7dc5542e93ae9cd76f
//! ")[..]);
//! # }