code: def get_activity_photos(self, activity_id, size=None, only_instagram=False):
          
          params = {}
  
          if not only_instagram:
              params['photo_sources'] = 'true'
  
          if size is not None:
              params['size'] = size
  
          result_fetcher = functools.partial(self.protocol.get,
                                             '/activities/{id}/photos',
                                             id=activity_id, **params)
  
          return BatchedResultsIterator(entity=model.ActivityPhoto,
                                        bind_client=self,
                                        result_fetcher=result_fetcher)
docs: Gets the photos from an activity.
  
          http://strava.github.io/api/v3/photos/
  
          :param activity_id: The activity for which to fetch kudos.
          :type activity_id: int
  
          :param size: the requested size of the activity's photos. URLs for the photos will be returned that best match
                      the requested size. If not included, the smallest size is returned
          :type size: int
  
          :param only_instagram: Parameter to preserve legacy behavior of only returning Instagram photos.
          :type only_instagram: bool
  
          :return: An iterator of :class:`stravalib.model.ActivityPhoto` objects.
          :rtype: :class:`BatchedResultsIterator`