interface IFeiRouter {
    // ----------- state changing api -----------

    function buyFei(
        uint256 minReward,
        uint256 amountOutMin,
        address to,
        uint256 deadline
    ) external payable returns (uint256 amountOut);

    function sellFei(
        uint256 maxPenalty,
        uint256 amountIn,
        uint256 amountOutMin,
        address to,
        uint256 deadline
    ) external returns (uint256 amountOut);
}
/// @title FeiRouter interface
/// @author Fei Protocol
function buyFei(
    uint256 minReward,
    uint256 amountOutMin,
    address to,
    uint256 deadline
) external payable returns (uint256 amountOut);

// ----------- state changing api -----------