Creating Option menu in Android Kotlin

main_menu.xml

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:id="@+id/mm_signout"
        android:icon="@drawable/ic_exit_to_app_black_24dp"
        android:title="SignOut"
        app:showAsAction="ifRoom" />
    <item android:id="@+id/help"
        android:icon="@drawable/ic_help_outline_black_24dp"
        android:title="Help" />
</menu>

option_menu_android.kt

override fun onCreateOptionsMenu(menu: Menu): Boolean {
        val inflater = menuInflater
        inflater.inflate(R.menu.main_menu, menu) //your file name
        return super.onCreateOptionsMenu(menu)
    }


    override fun onOptionsItemSelected(item: MenuItem): Boolean {

        when (item.getItemId()) {
            R.id.mm_signout -> {
                mAuth.signOut()
                return true
            }
             
            R.id.help ->{
                return true
            }
            else -> return super.onOptionsItemSelected(item)
        }
    }