function calcLpTokenSupply(
    uint256[] memory reserves,
    bytes memory data
) public view returns (uint256 lpTokenSupply) {
    if (reserves[0] == 0 && reserves[1] == 0) return 0;
    uint256[] memory decimals = decodeWellData(data);
    // scale reserves to 18 decimals.
    uint256[] memory scaledReserves = getScaledReserves(reserves, decimals);

    uint256 Ann = a * N * N;

    uint256 sumReserves = scaledReserves[0] + scaledReserves[1];
    if (sumReserves == 0) return 0;
    lpTokenSupply = sumReserves;
    for (uint256 i = 0; i < 255; i++) {
        uint256 dP = lpTokenSupply;
        // If division by 0, this will be borked: only withdrawal will work. And that is good
        dP = dP * lpTokenSupply / (scaledReserves[0] * N);
        dP = dP * lpTokenSupply / (scaledReserves[1] * N);
        uint256 prevReserves = lpTokenSupply;
        lpTokenSupply = (Ann * sumReserves / A_PRECISION + (dP * N)) * lpTokenSupply
            / (((Ann - A_PRECISION) * lpTokenSupply / A_PRECISION) + ((N + 1) * dP));
        // Equality with the precision of 1
        if (lpTokenSupply > prevReserves) {
            if (lpTokenSupply - prevReserves <= 1) return lpTokenSupply;
        } else {
            if (prevReserves - lpTokenSupply <= 1) return lpTokenSupply;
        }
    }
}
        if (lpTokenSupply > prevReserves) {
            if (lpTokenSupply - prevReserves <= 1) return lpTokenSupply;
        } else {
            if (prevReserves - lpTokenSupply <= 1) return lpTokenSupply;
        }
    }
+   revert("LP token supply calculation did not converge");
}
