function doTransfer(uint64 from, uint64 to, uint _amount) internal {
        uint amount = callPlugins(true, from, to, _amount);
        if (from == to) { 
            return;
        }
        if (amount == 0) {
            return;
        }
        Pledge storage nFrom = findPledge(from);
        Pledge storage nTo = findPledge(to);
        require(nFrom.amount >= amount);
        nFrom.amount -= amount;
        nTo.amount += amount;

        Transfer(from, to, amount);
        callPlugins(false, from, to, amount);
    }