How to use the 0x.js.ZeroEx.NULL_ADDRESS function in 0x

//   //   console.log(result)
    //   // })
    // })

    // zeroEx.tokenRegistry.getTokensAsync().then((tokens) => {
    //   console.log('tokens returned')
    //   commit('ADD_TOKENS', tokens)
    //   console.log('tokens:', tokens)
    //   const symbols = getters.tokenSymbols
    //   var index = symbols.indexOf('WETH')
    //   if (index !== -1) {
    //     symbols[index] = 'ETH'
    //   }
    //
    // })
    commit('SET_NULL_ADDRESS', ZeroEx.NULL_ADDRESS)
    zeroEx.etherToken.getContractAddressAsync().then((address) => {
      commit('SET_WETH_ADDRESS', address)
    })
    zeroEx.exchange.getZRXTokenAddressAsync().then((address) => {
      commit('SET_ZRX_ADDRESS', address)
    })
    zeroEx.exchange.getContractAddressAsync().then((address) => {
      commit('SET_EXCHANGE_ADDRESS', address)
    })
    zeroEx.getAvailableAddressesAsync().then((addresses) => {
      commit('SET_ADDRESSES', addresses)
    })
  },
  addTokenAddress ({commit}, address) {

const mainAsync = async () => {
    // const tokens = transformToTokens(tokensToAddJSON);
    const tokens = TOKENS_TO_ADD;
    const provider = providerFactory.getLedgerProvider();
    const zeroEx = new ZeroEx(provider, ZERO_EX_CONFIG);
    const accounts = await zeroEx.getAvailableAddressesAsync();
    const primaryAccount = _.head(accounts);
    console.log(`Primary account address: ${primaryAccount}`);

    const existingTokens = await zeroEx.tokenRegistry.getTokensAsync();
    const existingTokenAddresses = _.map(existingTokens, token => token.address);
    for (const token of tokens) {
        if (!_.includes(existingTokenAddresses, token.address)) {
            console.log(`Attempting to add token symbol: ${token.symbol} address: ${token.address}`);
            const txHash = await zeroEx.tokenRegistry.addTokenAsync(token, primaryAccount || ZeroEx.NULL_ADDRESS);
            console.log(`Awaiting txHash: ${txHash}`);
            opn(`https://etherscan.io/tx/${txHash}`);
            const txReceipt = await zeroEx.awaitTransactionMinedAsync(txHash);
            console.log(`Added receipt: ${JSON.stringify(txReceipt)}`);
        }
    }
};

const setTakerAllowTxHash = await zeroEx.token.setUnlimitedProxyAllowanceAsync(WETH_ADDRESS, takerAddress);
    await zeroEx.awaitTransactionMinedAsync(setTakerAllowTxHash);
    console.log('Taker allowance mined...');

    // Deposit WETH
    const ethAmount = new BigNumber(1);
    const ethToConvert = ZeroEx.toBaseUnitAmount(ethAmount, DECIMALS); // Number of ETH to convert to WETH

    const convertEthTxHash = await zeroEx.etherToken.depositAsync(WETH_ADDRESS, ethToConvert, takerAddress);
    await zeroEx.awaitTransactionMinedAsync(convertEthTxHash);
    console.log(`${ethAmount} ETH -> WETH conversion mined...`);

    // Generate order
    const order = {
        maker: makerAddress,
        taker: ZeroEx.NULL_ADDRESS,
        feeRecipient: ZeroEx.NULL_ADDRESS,
        makerTokenAddress: ZRX_ADDRESS,
        takerTokenAddress: WETH_ADDRESS,
        exchangeContractAddress: EXCHANGE_ADDRESS,
        salt: ZeroEx.generatePseudoRandomSalt(),
        makerFee: new BigNumber(0),
        takerFee: new BigNumber(0),
        makerTokenAmount: ZeroEx.toBaseUnitAmount(new BigNumber(0.2), DECIMALS), // Base 18 decimals
        takerTokenAmount: ZeroEx.toBaseUnitAmount(new BigNumber(0.3), DECIMALS), // Base 18 decimals
        expirationUnixTimestampSec: new BigNumber(Date.now() + 3600000), // Valid for up to an hour
    };

    // Create orderHash
    const orderHash = ZeroEx.getOrderHashHex(order);

    // Signing orderHash -> ecSignature

await zeroEx.awaitTransactionMinedAsync(setTakerAllowTxHash);
    console.log('Taker allowance mined...');

    // Deposit WETH
    const ethAmount = new BigNumber(1);
    const ethToConvert = ZeroEx.toBaseUnitAmount(ethAmount, DECIMALS); // Number of ETH to convert to WETH

    const convertEthTxHash = await zeroEx.etherToken.depositAsync(WETH_ADDRESS, ethToConvert, takerAddress);
    await zeroEx.awaitTransactionMinedAsync(convertEthTxHash);
    console.log(`${ethAmount} ETH -> WETH conversion mined...`);

    // Generate order
    const order = {
        maker: makerAddress,
        taker: ZeroEx.NULL_ADDRESS,
        feeRecipient: ZeroEx.NULL_ADDRESS,
        makerTokenAddress: ZRX_ADDRESS,
        takerTokenAddress: WETH_ADDRESS,
        exchangeContractAddress: EXCHANGE_ADDRESS,
        salt: ZeroEx.generatePseudoRandomSalt(),
        makerFee: new BigNumber(0),
        takerFee: new BigNumber(0),
        makerTokenAmount: ZeroEx.toBaseUnitAmount(new BigNumber(0.2), DECIMALS), // Base 18 decimals
        takerTokenAmount: ZeroEx.toBaseUnitAmount(new BigNumber(0.3), DECIMALS), // Base 18 decimals
        expirationUnixTimestampSec: new BigNumber(Date.now() + 3600000), // Valid for up to an hour
    };

    // Create orderHash
    const orderHash = ZeroEx.getOrderHashHex(order);

    // Signing orderHash -> ecSignature
    const shouldAddPersonalMessagePrefix = false;

const mainAsync = async () => {
    const provider = providerFactory.getLedgerProvider();
    const zeroEx = new ZeroEx(provider, ZERO_EX_CONFIG);
    const accounts = await zeroEx.getAvailableAddressesAsync();
    const primaryAccount = _.head(accounts);
    console.log(`Primary account address: ${primaryAccount}`);
    const tokenAddresses = await zeroEx.tokenRegistry.getTokenAddressesAsync();
    for (const addressToRemove of TOKEN_ADDRESSES_TO_REMOVE) {
        console.log(`Attempting to remove token address: ${addressToRemove}`);
        const index = _.indexOf(tokenAddresses, addressToRemove);
        if (index >= 0) {
            const txHash = await zeroEx.tokenRegistry.removeTokenAsync(
                addressToRemove,
                new BigNumber(index),
                primaryAccount || ZeroEx.NULL_ADDRESS,
            );
            console.log(`Awaiting txHash: ${txHash}`);
            const txReceipt = await zeroEx.awaitTransactionMinedAsync(txHash);
            console.log(`Removed receipt: ${JSON.stringify(txReceipt)}`);
        } else {
            console.log(`Could not find token address: ${addressToRemove}`);
        }
    }
};