Function encode_rs256_pem 

pub fn encode_rs256_pem<H, C>(
    header: &H,
    claims: &C,
    private_key_pem: &[u8],
) -> Result<String>
where
    H: Serialize,
    C: Serialize,

Encode a JWS compact JWT using an RSA private key in PKCS#8 PEM format.