code: def get_reviews(self, publisher_name, extension_name, count=None, filter_options=None, before_date=None, after_date=None):
          
          route_values = {}
          if publisher_name is not None:
              route_values['publisherName'] = self._serialize.url('publisher_name', publisher_name, 'str')
          if extension_name is not None:
              route_values['extensionName'] = self._serialize.url('extension_name', extension_name, 'str')
          query_parameters = {}
          if count is not None:
              query_parameters['count'] = self._serialize.query('count', count, 'int')
          if filter_options is not None:
              query_parameters['filterOptions'] = self._serialize.query('filter_options', filter_options, 'str')
          if before_date is not None:
              query_parameters['beforeDate'] = self._serialize.query('before_date', before_date, 'iso-8601')
          if after_date is not None:
              query_parameters['afterDate'] = self._serialize.query('after_date', after_date, 'iso-8601')
          response = self._send(http_method='GET',
                                location_id='5b3f819f-f247-42ad-8c00-dd9ab9ab246d',
                                version='5.1-preview.1',
                                route_values=route_values,
                                query_parameters=query_parameters)
          return self._deserialize('ReviewsResult', response)
docs: GetReviews.
          [Preview API] Returns a list of reviews associated with an extension
          :param str publisher_name: Name of the publisher who published the extension
          :param str extension_name: Name of the extension
          :param int count: Number of reviews to retrieve (defaults to 5)
          :param str filter_options: FilterOptions to filter out empty reviews etcetera, defaults to none
          :param datetime before_date: Use if you want to fetch reviews older than the specified date, defaults to null
          :param datetime after_date: Use if you want to fetch reviews newer than the specified date, defaults to null
          :rtype: :class:`<ReviewsResult> <azure.devops.v5_1.gallery.models.ReviewsResult>`