    function _isSolvent(
        address user,
        uint256 _exchangeRate
    ) internal view returns (bool) {
        // accrue must have already been called!
        uint256 borrowPart = userBorrowPart[user];
        if (borrowPart == 0) return true;
        uint256 collateralShare = userCollateralShare[user];
        if (collateralShare == 0) return false;

        Rebase memory _totalBorrow = totalBorrow;

        return
            yieldBox.toAmount(
                collateralId,
                collateralShare *
                    (EXCHANGE_RATE_PRECISION / FEE_PRECISION) *
                    collateralizationRate,
                false
            ) >=
            // Moved exchangeRate here instead of dividing the other side to preserve more precision
            (borrowPart * _totalBorrow.elastic * _exchangeRate) /
                _totalBorrow.base;
    }
        uint256 liquidationStartsAt = (collateralPartInAssetScaled *
            collateralizationRate) / (10 ** ratesPrecision);
