public function help($width = 0)
    {
        $name = $this->_name;
        if (strlen($name) < $width) {
            $name = str_pad($name, $width, ' ');
        }
        $optional = '';
        if (!$this->isRequired()) {
            $optional = ' <comment>(optional)</comment>';
        }
        if ($this->_choices) {
            $optional .= sprintf(' <comment>(choices: %s)</comment>', implode('|', $this->_choices));
        }

        return sprintf('%s%s%s', $name, $this->_help, $optional);
    }