Exemplo de criação de shortcode com código existente

functions.php

<?php 

add_shortcode("star_rating", "fn_star_ratings");

function fn_star_ratings($atts, $content=null){
	$data = shortcode_atts(["id" => 0], $atts); 
	return kk_star_ratings($data["id"]);
}

add_shortcode("star_rating_get", "fn_star_rating_get");

function fn_star_rating_get($atts, $content){
	
	$data = shortcode_atts(["total" => 10], $atts); 
	$posts =  kk_star_ratings_get($data["total"]);
	$response = "";
	
	foreach($posts as $p) {
		$response .= "<li>".$p->ratings."</li>";
	}
	return $response;
}