```\nfunction _takeDonationFee(uint256 tDonation) private {\n    uint256 currentRate = _getRate();\n    uint256 rDonation = tDonation.mul(currentRate);\n    _rOwned[_donationAddress] = _rOwned[_donationAddress].add(rDonation);\n    if (_isExcluded[_donationAddress])\n        _tOwned[_donationAddress] = _tOwned[_donationAddress].add(\n            tDonation\n        );\n}\n```\n