Function process_prekey_bundle 

pub async fn process_prekey_bundle<R>(
    remote_address: &ProtocolAddress,
    session_store: &mut dyn SessionStore,
    identity_store: &mut dyn IdentityKeyStore,
    bundle: &PreKeyBundle,
    now: SystemTime,
    csprng: &mut R,
) -> Result<(), SignalProtocolError>
where
    R: Rng + CryptoRng,