    function addBalance(address account, uint256 weiAmount, uint256 tokenAmount) public onlyOperator {
        if (!_contributors[account].exists) {
            _addresses.push(account);
            _contributors[account].exists = true;
        }
        _contributors[account].weiAmount = _contributors[account].weiAmount.add(weiAmount);
        _contributors[account].tokenAmount = _contributors[account].tokenAmount.add(tokenAmount);
        _totalWeiRaised = _totalWeiRaised.add(weiAmount);
        _totalSoldTokens = _totalSoldTokens.add(tokenAmount);
    }