title: PHP Error: Call to Undefined Function
body: <p>I have two methods in a PHP class:</p>
  
  <pre><code>    public static function sID($urlID) {
              return base_convert($urlID, 10, 62) - 239000;
      }
  
      public static function load($urlID) {
              if ($urlID = "" || !is_numeric($urlID)) return 0;
              $id = sID($urlID); // ERROR ON THIS LINE
      }
  </code></pre>
  
  <p>I am getting the error:  </p>
  
  <blockquote>
    <p>Fatal error: Call to undefined function sID()</p>
  </blockquote>
  
  <p>I have looked around online but amazingly enough, haven't found any solution to this seemingly simple problem.  Is there a syntax error or otherwise?</p>