How to call function from other JS File in React Native?

So i have a Drawer.Js using 'react-native-off-canvas-menu' where the sole purpose is to open and close the drawer. The problem is that this drawer will only open and close with gesture (slide left/right). I want to bind this open and close function with a button. The problem is it shows an error when i try to call function handleClick from Home.Js to my Drawer.Js

Inside my Drawer.Js

class FirstScreen extends Component {

constructor(props) {
super(props);
this.state = {
  menuOpen: false
};
this.handleClick = this.handleMenu.bind(this);
}

handleMenu() {
 const { menuOpen } = this.state;
 this.setState({
  menuOpen: !menuOpen
  });
  }
  // Some Render Method Where i tried to create a button, and calling 
     this.handleMenu() on the onPress event, and it's successful

  *//After the Render Method

   export function a() {
    return this.handleClick();
    }

I am also using react native router flux which the first route of my apps is going to Home.js, where in Home.js i am going to put a button to trigger the drawer to open.

Here's my code for Home.js *//Some Import

   import { a } from './Drawer';

 class Home extends Component {

    constructor(props) {
     super(props);
      this.handleKlik = this.handleKlik.bind(this);
     }

     handleKlik() {
        a();
      }

     *// Render Method Start
      <View>
         <TouchableOpacity onPress={() => this.handleKlik()}>
            <View style={styles.btnContainer}>
             <Text style={styles.btnText}>{'Toggle'.toUpperCase()}
             </Text>
           </View>
         </TouchableOpacity>
      <View>

Well here in Home.js, when i tried to click the button, i received and error like 'undefined is not a function (evaluting 'this.handleClick')'.

Well i think i know the problem where my export function is probably the problem. Can anyone please elaborate on how can i fix this? i've read the tutorial and i can't seem to understand why it's so hard to call a function inside another Js Files in my project