code: function withNonceTracker(provider) {
    const nonceTracker = new NonceTrackerSubprovider()
    provider.engine._providers.unshift(nonceTracker)
    nonceTracker.setEngine(provider.engine)
    return provider
  }
docs: This function adds protection against the "nonce too low" error seen on some web3 provider server farms.  For more details see: https://ethereum.stackexchange.com/questions/44349/truffle-infura-on-mainnet-nonce-too-low-error