/**
  * Singleton method
  *
  * @return oxSeoEncoderTag
  */
 public static function getInstance()
 {
     // disable caching for test modules
     if (defined('OXID_PHP_UNIT')) {
         self::$_instance = modInstances::getMod(__CLASS__);
     }
     if (!self::$_instance instanceof oxSeoEncoderTag) {
         self::$_instance = oxNew('oxSeoEncoderTag');
         if (defined('OXID_PHP_UNIT')) {
             modInstances::addMod(__CLASS__, self::$_instance);
         }
     }
     if (defined('OXID_PHP_UNIT')) {
         // resetting cache
         self::$_instance->_aSeoCache = array();
     }
     return self::$_instance;
 }