logged in / logged out different menu

I want a different menu displayed for logged in users to normal visitors to the site. I have done this in the past with other themes easily but my usual code below is not working, it is in functions.php of a child theme. Any suggestions as to how to get this working please? (Currently on local dev site so no url)

//***** Login stuff
if( is_user_logged_in() ) { 
	$args['menu'] = 'logged-in';
} else { 
	$args['menu'] = 'logged-out';
} 
	return $args;
}
add_filter( 'wp_nav_menu_args', 'my_wp_nav_menu_args' );