public function call($command, array $parameters = array(), OutputInterface $output = null)
    {
        $parameters['command'] = $command;

        // Unless an output interface implementation was specifically passed to us we
        // will use the "NullOutput" implementation by default to keep any writing
        // suppressed so it doesn't leak out to the browser or any other source.
        $output = $output ?: new NullOutput;

        $input = new ArrayInput($parameters);

        return $this->find($command)->run($input, $output);
    }