interface ICurve {
    // solium-disable-next-line mixedcase
    function get_dy_underlying(int128 i, int128 j, uint256 dx) external view returns(uint256 dy);

    // solium-disable-next-line mixedcase
    function get_dy(int128 i, int128 j, uint256 dx) external view returns(uint256 dy);

    // solium-disable-next-line mixedcase
    function exchange_underlying(int128 i, int128 j, uint256 dx, uint256 minDy) external;

    // solium-disable-next-line mixedcase
    function exchange(int128 i, int128 j, uint256 dx, uint256 minDy) external;
}
function get_dy(int128 i, int128 j, uint256 dx) external view returns(uint256 dy);
// solium-disable-next-line mixedcase