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: custom_header.rs
    path of file: ./repos/jsonwebtoken/examples
    
    the code of the file until where you have to start completion: use serde::{Deserialize, Serialize};

use jsonwebtoken::errors::ErrorKind;
use jsonwebtoken::{decode, encode, Algorithm, DecodingKey, EncodingKey, He
    
fn main() {
    let my_claims =
        Claims { sub: "b@b.com".to_owned(), company: "ACME".to_owned(), exp: 10000000000 };
    let key = b"secret";

    let header =
        Header { kid: Some("signing_key".to_owned()), alg: Algorithm::HS512, ..Default::default() };

    let token = match encode(&header, &my_claims, &EncodingKey::from_secret(key)) {
        Ok(t) => t,
        Err(_) => panic!(), // in practice you would return the error
    };
    println!("{:?}", token);

    let token_data = match decode::<Claims>(
        &token,
        &DecodingKey::from_secret(key),
        &Validation::new(Algorithm::HS512),
    ) {
        Ok(c) => c,
        Err(err) => match *err.kind() {
            ErrorKind::InvalidToken => panic!(), // Example on how to handle a specific error
            _ => panic!(),
        },
    };
    println!("{:?}", token_data.claims);
    println!("{:?}", token_data.header);
}