function convertToShares(uint256 assets) public view override returns (uint256 shares) {
    uint256 supply = totalSupply();
    if (supply == 0) {
        // Scales assets by the value of a single unit of fCash
        uint256 unitfCashValue = _getPresentValue(uint256(Constants.INTERNAL_TOKEN_PRECISION));
        return (assets * uint256(Constants.INTERNAL_TOKEN_PRECISION)) / unitfCashValue;
    }

    return (assets * totalSupply()) / totalAssets();
}
function previewWithdraw(uint256 assets) public view override returns (uint256 shares) {
    if (hasMatured()) {
        shares = convertToShares(assets);
    } else {
        // If withdrawing non-matured assets, we sell them on the market (i.e. borrow)
        (uint16 currencyId, uint40 maturity) = getDecodedID();
        (shares, /* */, /* */) = NotionalV2.getfCashBorrowFromPrincipal(
            currencyId,
            assets,
            maturity,
            0,
            block.timestamp,
            true
        );
    }
}
