protected function showHelp()
    {
        $this->log('Usage:', 'yellow');
        $this->log('  vobject [options] command [arguments]');
        $this->log('');
        $this->log('Options:', 'yellow');
        $this->log($this->colorize('green', '  -q            ')."Don't output anything.");
        $this->log($this->colorize('green', '  -help -h      ').'Display this help message.');
        $this->log($this->colorize('green', '  --format      ').'Convert to a specific format. Must be one of: vcard, vcard21,');
        $this->log($this->colorize('green', '  --forgiving   ').'Makes the parser less strict.');
        $this->log('                vcard30, vcard40, icalendar20, jcal, jcard, json, mimedir.');
        $this->log($this->colorize('green', '  --inputformat ').'If the input format cannot be guessed from the extension, it');
        $this->log('                must be specified here.');
        // Only PHP 5.4 and up
        if (version_compare(PHP_VERSION, '5.4.0') >= 0) {
            $this->log($this->colorize('green', '  --pretty      ').'json pretty-print.');
        }
        $this->log('');
        $this->log('Commands:', 'yellow');
        $this->log($this->colorize('green', '  validate').' source_file              Validates a file for correctness.');
        $this->log($this->colorize('green', '  repair').' source_file [output_file]  Repairs a file.');
        $this->log($this->colorize('green', '  convert').' source_file [output_file] Converts a file.');
        $this->log($this->colorize('green', '  color').' source_file                 Colorize a file, useful for debbugging.');
        $this->log(
        <<<HELP

If source_file is set as '-', STDIN will be used.
If output_file is omitted, STDOUT will be used.
All other output is sent to STDERR.

HELP
        );

        $this->log('Examples:', 'yellow');
        $this->log('   vobject convert contact.vcf contact.json');
        $this->log('   vobject convert --format=vcard40 old.vcf new.vcf');
        $this->log('   vobject convert --inputformat=json --format=mimedir - -');
        $this->log('   vobject color calendar.ics');
        $this->log('');
        $this->log('https://github.com/fruux/sabre-vobject', 'purple');
    }