uint256 payAmount = (((realAmount * getAssetPrice()) / 1e18) * getDutchAuctionDiscountPrice()) / 10000 = 2e17 * 1000e18 / 1e18 = 200e18
uint256 sharesAmount = _EUSDAmount.mul(_totalShares).div(totalMintedEUSD) = 200e18 * (200e18 + 1) / (200e18 + 1) = 200e18
sharesAmount = _EUSDAmount.mul(_totalShares).div(totalMintedEUSD) = 4000e18 * 1 / (200e18 + 1) = 19
function rigidRedemption(address provider, uint256 eusdAmount) external virtual {
        // ...
        uint256 brnedShares = _repay(msg.sender, provider, eusdAmount);
        eusdAmount = getMintedEUSDByShares(brnedShares);
        //...
    }
uint256 sharesAmount = EUSD.getSharesByMintedEUSD(payAmount - income);
            if (sharesAmount == 0) {
                //EUSD totalSupply is 0: assume that shares correspond to EUSD 1-to-1
                sharesAmount = (payAmount - income);
            }
