EDD "Already Logged In" message for [edd_register]

gistfile1.php

<?php // DO NOT COPY THIS LINE

/**
 * Show message instead of registration form [edd_register] when user is logged in
 */
function sd_already_registered_message() {
	if ( is_user_logged_in() ) {
		
		// custom message
		$message = "You're already logged in.";
		return $message;
	}
}
add_filter( 'edd_register_form', 'sd_already_registered_message' );