I have module where I need to use the stack navigator in the LoginScreen however when the user successfully login drawer navigator will implement instead of stack navigator. Right now i got an error it says.

> 
> functions are not valid as a React child. This may happen if you return a Component instead of from render. Or maybe you meant to call this function rather than return it.
> 
> 
> 

What I have on my app.js

```
    const Stack = createStackNavigator();
const Drawer = createDrawerNavigator();

const UnauthenticatedScreen = () => {   
        <Stack.Navigator>
                <Stack.Screen 
                    name="Login" 
                    component={Login} 
                    options=
                    {{
                        headerShown: false,
                    }}
                />
                <Stack.Screen 
                    name="Registration" 
                    component={Register} 
                    options={{
                        headerStyle: {
                            backgroundColor: '#4ABDFF'
                        },
                        headerTitleStyle: {
                            color: '#fff',
                        },
                        headerTintColor:'#fff',
                    }}

                />

                <Stack.Screen 
                    name="Privacy" 
                    component={PrivacyPolicy} 
                    options={{
                        headerStyle: {
                            backgroundColor: '#4ABDFF'
                        },
                        headerTitleStyle: {
                            color: '#fff',
                        },
                        headerTitle:'Privacy Policy',
                        headerTintColor:'#fff',
                    }}
                />

                <Stack.Screen
                    name="RegistrationSuccess"
                    component={RegistrationSuccess}
                    options=
                    {{
                        headerShown: false,
                    }}
                />
        </Stack.Navigator>

}

function AuthenticatedDriverScreen() {
    <Drawer.Navigator initialRouteName="DriverDashboard">
      <Drawer.Screen
        name="DriverDashboard"
        component={DriverDashboard}
        options={{ drawerLabel: 'Home' }}
      />
    </Drawer.Navigator>
}

function App() {
    const isLogin = false;
    return (
        <NavigationContainer>
         {isLogin ? AuthenticatedDriverScreen : UnauthenticatedScreen}
        </NavigationContainer>

    )
}

export default App;

```

Very well appreciated your help guys.