def handle_help_command(self, scan_et):
        """ Handles <help> command.

        @return: Response string for <help> command.
        """
        help_format = scan_et.attrib.get('format')
        if help_format is None or help_format == "text":
            # Default help format is text.
            return simple_response_str('help', 200, 'OK',
                                       self.get_help_text())
        elif help_format == "xml":
            text = self.get_xml_str(self.commands)
            return simple_response_str('help', 200, 'OK', text)
        raise OSPDError('Bogus help format', 'help')
Handles <help> command.

        @return: Response string for <help> command.