constructor(address _governance) {
        // sets governance as owner
        _transferOwnership(_governance);

        uint256 chainId;
        assembly {
            chainId := chainid()
        }

        EIP712_DOMAIN_TYPEHASH = keccak256(
            abi.encode(
                keccak256('EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)'),
                keccak256(bytes('GOLOM.IO')),
                keccak256(bytes('1')),
                chainId,
                address(this)
            )
        );
    }
