How to use the @0x/contracts-test-utils.constants.ZERO_AMOUNT function in @0x/contracts-test-utils

environment.provider,
            environment.txDefaults,
            exchangeArtifacts,
            new BigNumber(chainId),
        );
        const assetProxyOwner = await AssetProxyOwnerContract.deployFrom0xArtifactAsync(
            multisigArtifacts.AssetProxyOwner,
            environment.provider,
            txDefaults,
            multisigArtifacts,
            [],
            [],
            [],
            [owner],
            new BigNumber(1),
            constants.ZERO_AMOUNT,
        );
        const tokens = await DeploymentManager._deployTokenContractsAsync(environment, txDefaults);
        const staking = await DeploymentManager._deployStakingContractsAsync(
            environment,
            owner,
            txDefaults,
            tokens,
            assetProxies,
        );

        // Configure the asset proxies with the exchange and the exchange with the staking contracts.
        await DeploymentManager._configureAssetProxiesWithExchangeAsync(assetProxies, exchange, owner);
        await DeploymentManager._configureExchangeWithStakingAsync(exchange, staking, owner);

        // Authorize the asset-proxy owner in the staking proxy and in the zrx vault.
        await staking.stakingProxy.addAuthorizedAddress.awaitTransactionSuccessAsync(assetProxyOwner.address, {

constructor(
        public currentEpoch: BigNumber = stakingConstants.INITIAL_EPOCH,
        public currentEpochBalance: BigNumber = constants.ZERO_AMOUNT,
        public nextEpochBalance: BigNumber = constants.ZERO_AMOUNT,
    ) {}
}

function emptyFillResults(): FillResults {
    return {
        makerAssetFilledAmount: constants.ZERO_AMOUNT,
        takerAssetFilledAmount: constants.ZERO_AMOUNT,
        makerFeePaid: constants.ZERO_AMOUNT,
        takerFeePaid: constants.ZERO_AMOUNT,
    };
}

function emptyFillResults(): FillResults {
    return {
        makerAssetFilledAmount: constants.ZERO_AMOUNT,
        takerAssetFilledAmount: constants.ZERO_AMOUNT,
        makerFeePaid: constants.ZERO_AMOUNT,
        takerFeePaid: constants.ZERO_AMOUNT,
    };
}

function emptyFillResults(): FillResults {
    return {
        makerAssetFilledAmount: constants.ZERO_AMOUNT,
        takerAssetFilledAmount: constants.ZERO_AMOUNT,
        makerFeePaid: constants.ZERO_AMOUNT,
        takerFeePaid: constants.ZERO_AMOUNT,
    };
}

function emptyMatchedFillResults(): MatchedFillResults {
    return {
        left: emptyFillResults(),
        right: emptyFillResults(),
        profitInLeftMakerAsset: constants.ZERO_AMOUNT,
        profitInRightMakerAsset: constants.ZERO_AMOUNT,
    };
}

function emptyFillResults(): FillResults {
    return {
        makerAssetFilledAmount: constants.ZERO_AMOUNT,
        takerAssetFilledAmount: constants.ZERO_AMOUNT,
        makerFeePaid: constants.ZERO_AMOUNT,
        takerFeePaid: constants.ZERO_AMOUNT,
    };
}

constructor(
        public currentEpoch: BigNumber = stakingConstants.INITIAL_EPOCH,
        public currentEpochBalance: BigNumber = constants.ZERO_AMOUNT,
        public nextEpochBalance: BigNumber = constants.ZERO_AMOUNT,
    ) {}
}