WordPress Custom Rewrite Rule

functions.php

/**
* WordPress Custom Rewrite Rule
* @author: takien
* @version: 1.0
* @url: http://takien.com
*/
function create_rewrite_rules() {
	global $wp_rewrite;
	
	$rewrite_tag = '%coba%';
	$wp_rewrite->add_rewrite_tag( $rewrite_tag, '(.+?)', 'coba=' );
	$rewrite_keywords_structure = $wp_rewrite->root . "coba/$rewrite_tag";
	$new_rule = $wp_rewrite->generate_rewrite_rules( $rewrite_keywords_structure );
	$wp_rewrite->rules = $new_rule + $wp_rewrite->rules;
	
	return $wp_rewrite->rules;
}

function add_custom_page_variables( $public_query_vars ) {
	$public_query_vars[] = 'coba';
	return $public_query_vars;
}

add_action( 'generate_rewrite_rules', 'create_rewrite_rules' );
add_filter( 'query_vars', 'add_custom_page_variables' );

$coba = get_query_var('coba');