def METHOD_NAME(self, episodes):
    if not self.config.context_menu:
        return None
    if not all(e.was_downloaded(and_exists=True) for e in episodes):
        return None
    if not any(self._check_source(episode) for episode in episodes):
        return None
    menu_item = _('Convert to %(format)s') % {'format': self.config.output_format}
    return [(menu_item, self._convert_episodes)]