in fastpay_core/src/fastpay_smart_contract.rs [36:48]
    fn handle_funding_transaction(
        &mut self,
        transaction: FundingTransaction,
    ) -> Result<(), failure::Error>;
    /// Finalize a transfer from FastPay to Primary.
    fn handle_redeem_transaction(
        &mut self,
        transaction: RedeemTransaction,
    ) -> Result<(), failure::Error>;
}
impl FastPaySmartContract for FastPaySmartContractState {