public function getTokenModel($modelClass = 'StandardTokenModel')
    {
        if (! isset($this->_tokenModels[$modelClass])) {
            $this->_tokenModels[$modelClass] = $this->_loadClass('Model_' . $modelClass, true);
            $this->_tokenModels[$modelClass]->applyFormatting();
        }

        return $this->_tokenModels[$modelClass];
    }