text: import React , { useState, useEffect } from 'react';
  import { StyleSheet, Text, View } from 'react-native';
  import { BackHandler } from "react-native";
  
  /* useBackButton */
  function useBackButton(navigation) {
      useEffect(() => {
        BackHandler.addEventListener("hardwareBackPress", navigation.goBack());
    
        return () => {
          BackHandler.removeEventListener(
            "hardwareBackPress",
            navigation.goBack()
          );
        };
      }, [navigation]);
    }
  
  export const Main = ({ navigation }) => {
      //utilize custom hook
      //useBackButton(navigation);
      
      return (
          <View>
              <Text> Hello </Text>
          </View>
      );
  }
  