GoCryptobotRandom.sol

function _shuffle(uint8[] deck) internal {
    require(deck.length < 256);

    uint8 deckLength = uint8(deck.length);
    uint8 random;
    for (uint8 i = 0; i < deckLength; i++) {
        if (i % 32 == 0) {
            randomBytes = keccak256(randomBytes);
        }
        random = uint8(randomBytes[i % 32]) % (deckLength - i);

        if (random != deckLength - 1 - i) {
            deck[random] ^= deck[deckLength - 1 - i];
            deck[deckLength - 1 - i] ^= deck[random];
            deck[random] ^= deck[deckLength - 1 - i];
        }
    }
}