React Native – async/await does not work

Is it possible to use async/await outside of classes?
For example I use AsyncStorage to store access token and want to get this token before StackNavigator will be initialized.

container.js

import React from 'react';
import { StackNavigator } from 'react-navigation';
import PairingView from '../components/PairingView';
import MainView from '../components/MainView';
import { getTokenFromStorageAsync } from '../helpers/asyncStorageHelper';

const accessToken = getTokenFromStorageAsync().done();
console.log(accessToken);   <---------- undefined

const AppNavigator = StackNavigator({
  PairingRoute: {
    screen: PairingView
  },
  MainRoute: {
    screen: MainView
  }
}, {
  initialRouteName: (accessToken == null) ? 'PairingRoute' : 'MainRoute',
  initialRouteParams: {
    token: accessToken
  }
});

const App = () => (
  <AppNavigator />
);

export default App;

asyncStorageHelper.js

import { AsyncStorage } from 'react-native';

export const getTokenFromStorageAsync = async () => {
  try {
    const value = await AsyncStorage.getItem('@nfs:token');
    console.log(value);   <---------- access token
    if (value != null)
      return value;
  } catch (err) {
    console.error(err);
  }
  return undefined;
};


Source: stackoverflow-javascript