<?php


	add_action( 'new_hook', 'sushi_add_a_title');
function sushi_add_a_title(){
	$title = 'hello world!';
  	echo apply_filters('a_nice_title' , $title );
}

?>

<?php
	add_filter('a_nice_title', 'replace_string');
	function replace_string($title){
		$title = str_replace("hello world!", "Hi world!", $title);
	return $title;
}