Class 'REST_Controller' not found with Codeigniter and REST API service
<p>I'm having a problem with the popular REST API controller maintained by Chris Kacerguis. 
I've imported the three files Format.php, REST_Controller.php and rest.php and placed them in the proper locations in my codeIgniter file structure.
I created a Users controller that looks like this: </p>

<pre><code>&lt;?php

require_once APPPATH.'libraries/REST_Controller.php';

class Users extends REST_Controller{
    public function index_get()
    {
        // Display all users
        $this-&gt;response("Get method");
    }
    public function index_post()
    {
        // Create a new user
        $this-&gt;response("Post method");
    }
}
?&gt;
</code></pre>

<p>I keep getting a error message that says: "Class 'REST_Controller' not found" when I navigate to my endpoint: <a href="http://localhost/api_test/index.php/users" rel="nofollow noreferrer">http://localhost/api_test/index.php/users</a></p>

<p>Any idea what i'm doing wrong?</p>