Supply underlying asset

supply supplying an underlying asset to the protocol .

function supply(
    MarketParams memory marketParams,
    uint256 assets,
    uint256 shares,
    address onBehalf,
    bytes calldata data
) external returns (uint256, uint256) {
    Id id = marketParams.id();
    require(market[id].lastUpdate != 0, ErrorsLib.MARKET_NOT_CREATED);
    require(UtilsLib.exactlyOneZero(assets, shares), ErrorsLib.INCONSISTENT_INPUT);
    require(onBehalf != address(0), ErrorsLib.ZERO_ADDRESS);

    _accrueInterest(marketParams, id);

    if (assets > 0) shares = assets.toSharesDown(market[id].totalSupplyAssets, market[id].totalSupplyShares);
    else assets = shares.toAssetsUp(market[id].totalSupplyAssets, market[id].totalSupplyShares);

    position[id][onBehalf].supplyShares += shares;
    market[id].totalSupplyShares += shares.toUint128();
    market[id].totalSupplyAssets += assets.toUint128();

    emit EventsLib.Supply(id, msg.sender, onBehalf, assets, shares);

    if (data.length > 0) INatriumSupplyCallback(msg.sender).onNatriumSupply(assets, data);

    IERC20(marketParams.loanToken).safeTransferFrom(msg.sender, address(this), assets);

    return (assets, shares);
}