function wpdocs_check_logged_in() {
$current_user = wp_get_current_user();
if ( 0 == $current_user->ID ) {
    // Not logged in.
    echo "not logged in<br/>";
    $current_user->add_role( 'custom-guest', 'Custom Guest',
    array( 'read' => true,
           'upload_files' => true,
           'unfiltered_upload' => true ) );


} else {
    // Logged in.
    echo "I'm Logged in";
}

add_action( 'init', 'wpdocs_check_logged_in' );