public function toString($handler)
    {
        if (false === isset($this->text[$handler])) {
            throw new \Exception('Missing handler '.$handler.' for expression : '.var_export($handler, true));
        }

        return $this->text[$handler];
    }
public function toString($handler)
    {
        if (false === isset($this->text[$handler])) {
            throw new \Exception('Missing handler '.$handler.' for expression : '.var_export($handler, true));
        }

        return $this->text[$handler];
    }
@param string $handler

@return mixed
@throws \Exception