title: React Native fetch throws undefined is not a function evaluating ((0,_reactNative.fetch)
body: <p>Am new to react native, am trying to access remote url throws this error. "undefined is not a function evaluating ((0,_reactNative.fetch)". Not sure what am doing wrong; Please help. 
  Am using the latest version of react native 0.40</p>
  
  <pre><code>import React, { Component } from "react";
  import { 
    View, 
    Text,
    Button,
    fetch,
    NativeModules,
    NativeEventEmitter 
  } from "react-native";
  
  export default class VideoScreen extends Component {
      componentDidMount(){
         this.video();
      }
      video(){
         fetch('http://localhost:4200/token').then(function(res) {
           console.log(res.json());
  
          })
      }
  
  }
  </code></pre>