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: util.rs
    path of file: ./repos/akula/src/sentry/devp2p
    
    the code of the file until where you have to start completion: use super::types::*;
use ethereum_types::H256;
use hmac::{Hmac, Mac};
use se
    
pub fn hmac_sha256(key: &[u8], input: &[&[u8]], auth_data: &[u8]) -> H256 {
    let mut hmac = Hmac::<Sha256>::new_from_slice(key).unwrap();
    for input in input {
        hmac.update(input);
    }
    hmac.update(auth_data);
    H256::from_slice(&hmac.finalize().into_bytes())
}