docs: function(settings) {
        settings = settings || {};
  
        // if we got a string, instead of a settings object, use that string as the content
        if (typeof settings === 'string') {
          settings = { content: settings };
        }
  
        // add new settings to our settings object
        [
          'content',
          'content-url',
          'assets',
          'service-worker-url',
          'cache-version',
        ].forEach(function(settingName) {
          if (settings[settingName] !== undefined) {
            _settings[settingName] = settings[settingName];
          }
        });
  
        // Add scope setting
        if (settings['scope'] !== undefined) {
          _settings['registration-options']['scope'] = settings['scope'];
        }
      }