Example of https://gist.github.com/Z-M-Huang/572d85252f6be1749aa4b6cec98640d3

ExampleRandom.sol

contract Random is RandomClient {
    string public _serverSeed;
    string public _clientSeed;
    uint64 public _nonce;
    uint64 public _value;

    bool public verifiedResult;

    constructor() RandomClient() {
        _clientSeed = "123123123";
    }

    function getRandom() public {
        getRandomNumber(_clientSeed);
    }

    function verifyRandom() public {
        verifyRandomNumber(_serverSeed, _clientSeed, _nonce, _value);
    }

    function randomNumberReceivedCallback(bytes32, string memory serverSeed, string memory clientSeed,
        uint64 nonce, uint64 value) internal override {
            _serverSeed = serverSeed;
            _clientSeed = clientSeed;
            _nonce = nonce;
            _value = value;
        }
    
    
    function verifyRandomReceivedCallback(bytes32, bool value) internal override {
        verifiedResult = value;
    }
}