def clear(self):
        super(GroupedRequirements, self).clear()
        self.create_default_groups()
def _format_traceback(cls, traceback_lines, should_print_backtrace):
        if should_print_backtrace:
            traceback_string = "\n{}".format("".join(traceback_lines))
        else:
            traceback_string = " {}".format(cls._traceback_omitted_default_text)
        return traceback_string