code: def is_propagating(self, images, augmenter, parents, default):
          
          if self.propagator is None:
              return default
          else:
              return self.propagator(images, augmenter, parents, default)
docs: Returns whether an augmenter may call its children to augment an
          image. This is independent of the augmenter itself possible changing
          the image, without calling its children. (Most (all?) augmenters with
          children currently dont perform any changes themselves.)
  
          Returns
          -------
          bool
              If True, the augmenter may be propagate to its children. If False, it may not.