function _currentExchangeRate() internal view returns (uint256) {
    uint256 _totalSupplyAmount = _totalSupply();
    uint256 _totalSupplyToAssets = _convertToAssets(
      _totalSupplyAmount,
      _lastRecordedExchangeRate,
      Math.Rounding.Down
    );

    uint256 _withdrawableAssets = _yieldVault.maxWithdraw(address(this));

    if (_withdrawableAssets > _totalSupplyToAssets) {
      _withdrawableAssets = _withdrawableAssets - (_withdrawableAssets - _totalSupplyToAssets);
    }

    if (_totalSupplyAmount != 0 && _withdrawableAssets != 0) {
      return _withdrawableAssets.mulDiv(_assetUnit, _totalSupplyAmount, Math.Rounding.Down);
    }

    return _assetUnit;
  }
if (_totalSupplyAmount != 0 && _withdrawableAssets != 0) {
  assert(_withdrawableAssets.mulDiv(_assetUnit, _totalSupplyAmount, Math.Rounding.Down) <= _assetUnit);
  return _withdrawableAssets.mulDiv(_assetUnit, _totalSupplyAmount, Math.Rounding.Down);
}
if (_withdrawableAssets > _totalSupplyToAssets) {
  _withdrawableAssets = _withdrawableAssets - (_withdrawableAssets - _totalSupplyToAssets);
}
