protected function _displayHelp($command)
    {
        $format = 'text';
        if (!empty($this->args[0]) && $this->args[0] === 'xml') {
            $format = 'xml';
            $this->_io->setOutputAs(ConsoleOutput::RAW);
        } else {
            $this->_welcome();
        }

        $subcommands = $this->OptionParser->subcommands();
        $command = isset($subcommands[$command]) ? $command : null;

        return $this->out($this->OptionParser->help($command, $format));
    }