/**
  * Check if the account ID is valid.
  *
  * @return bool|null
  */
 public function has_valid_account_id()
 {
     /* Load the Emma API library. */
     require_once 'includes/api/Emma.php';
     /* Get the plugin settings */
     $settings = $this->get_plugin_settings();
     /* If any of the account information fields are empty, return null. */
     if (rgblank($settings['account_id']) || rgblank($settings['public_api_key']) || rgblank($settings['private_api_key'])) {
         return null;
     }
     $emma = new Emma($settings['account_id'], $settings['public_api_key'], $settings['private_api_key'], false);
     try {
         /* Run test request. */
         $emma->myGroups();
         return true;
     } catch (Exception $e) {
         /* Log that test failed based on HTTP code. */
         if ($e->getHttpCode() == 403) {
             $this->log_error(__METHOD__ . '(): API credentials are valid, Account ID is invalid; ' . $e->getMessage());
         }
         return false;
     }
 }