'use' is twice. (#160)

README.md

@@ -84,7 +84,7 @@ Before you dive into the various aspects of building a JavaScript web app, it is
 
 Prior to 2015, the last major update was ECMAScript 5.1, in 2011. However, in the recent years, JavaScript has suddenly seen a huge burst of improvements within a short span of time. In 2015, ECMAScript 2015 (previously called ECMAScript 6) was released and a ton of syntactic constructs were introduced to make writing code less unwieldy. If you are curious about it, Auth0 has written a nice article on the [history of JavaScript](https://auth0.com/blog/a-brief-history-of-javascript/). Till this day, not all browsers have fully implemented the ES2015 specification. Tools such as [Babel](https://babeljs.io/) enable developers to write ES2015 in their apps and Babel transpiles them down to ES5 to be compatible for browsers.
 
-Being familiar with both ES5 and ES2015 is crucial. ES2015 is still relatively new and a lot of open source code and Node.js apps are still written in ES5. If you are doing debugging in your browser console, you might not be able to use ES2015 syntax. On the other hand, documentation and example code for many modern libraries that we will introduce later below are still written in ES2015. At Grab, we use use [babel-preset-env](https://github.com/babel/babel-preset-env) to enjoy the productivity boost from the syntactic improvements the future of JavaScript provides and we have been loving it so far. `babel-preset-env` intelligently determines which Babel plugins are necessary (which new language features are not supported and have to be transpiled) as browsers increase native support for more ES language features. If you prefer using language features that are already stable, you may find that [babel-preset-stage-3](https://babeljs.io/docs/plugins/preset-stage-3/), which is a complete specification that will most likely be implemented in browsers, will be more suitable.
+Being familiar with both ES5 and ES2015 is crucial. ES2015 is still relatively new and a lot of open source code and Node.js apps are still written in ES5. If you are doing debugging in your browser console, you might not be able to use ES2015 syntax. On the other hand, documentation and example code for many modern libraries that we will introduce later below are still written in ES2015. At Grab, we use [babel-preset-env](https://github.com/babel/babel-preset-env) to enjoy the productivity boost from the syntactic improvements the future of JavaScript provides and we have been loving it so far. `babel-preset-env` intelligently determines which Babel plugins are necessary (which new language features are not supported and have to be transpiled) as browsers increase native support for more ES language features. If you prefer using language features that are already stable, you may find that [babel-preset-stage-3](https://babeljs.io/docs/plugins/preset-stage-3/), which is a complete specification that will most likely be implemented in browsers, will be more suitable.
 
 Spend a day or two revising ES5 and exploring ES2015. The more heavily used features in ES2015 include "Arrows and Lexical This", "Classes", "Template Strings", "Destructuring", "Default/Rest/Spread operators", and "Importing and Exporting modules".