pub fn child(&self, extrinsics_root: Hash, state: u64) -> Self {
        let mut header = Self {
            parent: hash(self),
            height: self.height + 1,
            extrinsics_root,
            state,
            consensus_digest: 0,
        };
        let mut nonce = 0;
        while hash(&header) > THRESHOLD {
            nonce += 1;
            header.consensus_digest = nonce;
        }
        header
    }

fn bc_5_heaviest_chain() {
    println!("test");
    let g = Header::genesis();

    let mut i = 0;
    let h_a1 = loop {
        let header = g.child(hash(&[i]), i);
        println!("{}", hash(&header) > THRESHOLD);
        // Extrinsics root hash must be higher than threshold (less work done)
        if hash(&header) > THRESHOLD {
            break header;
        }
        i += 1;
    };
}