function executeTrade(address trainerA, uint64 monA, address trainerB, uint64 monB) private
    {
        EtheremonDepositContract(depositAddress[trainerA]).sendMon(tradeAddress, trainerB, monA); 
        EtheremonDepositContract(depositAddress[trainerB]).sendMon(tradeAddress, trainerA, monB); 
    }