code: function(providerObject) {
    const fixedProviderObject = Object.assign({}, providerObject);
  
    // object has signTransaction
    if (typeof fixedProviderObject.signTransaction !== 'undefined') {
      // store old sign transaction method
      const oldSignTransactionMethod = fixedProviderObject.signTransaction;
  
      // build new provider object signTransaciton method
      fixedProviderObject.signTransaction = function(rawTx, cb) {
        // fire old callback
        oldSignTransactionMethod(fixEthereumJSTxObject(rawTx), cb);
      };
    }
  
    // return fixed provider object
    return fixedProviderObject;
  }
docs: fix signTransaction method with rawTx fix