fn main() -> Result<(), Box<dyn Error>> {
    tink_signature::init();
    // Other key templates can also be used.
    let kh = tink_core::keyset::Handle::new(&tink_signature::ecdsa_p256_key_template())?;
    let s = tink_signature::new_signer(&kh)?;

    let pt = b"this data needs to be signed";
    let a = s.sign(pt)?;
    println!("'{}' => {}", String::from_utf8_lossy(pt), hex::encode(&a));

    let pubkh = kh.public()?;
    let v = tink_signature::new_verifier(&pubkh)?;
    assert!(v.verify(&a, b"this data needs to be signed").is_ok());
    println!("Signature verified.");
    Ok(())
}