function batchSendTokens(address[] addresses, uint256[] _values) 
        public onlyOwnerAndContract
        returns (bool) {
        require(addresses.length == _values.length);
        require(addresses.length <= 20); 
        uint i = 0;
        uint len = addresses.length;
        for (;i < len; i++) {
            sendToken(addresses[i], _values[i]);
        }
        return true;
    }