code: def index_within_subset(self, indexable, subset_request,
                              sort_indices=False):
          if isinstance(subset_request, numbers.Integral):
              request, = self[[subset_request]]
          else:
              request = self[subset_request]
          if isinstance(request, numbers.Integral) or hasattr(request, 'step'):
              return indexable[request]
          if sort_indices:
              return self.sorted_fancy_indexing(indexable, request)
          if isinstance(indexable, (numpy.ndarray, h5py.Dataset)):
              return indexable[request]
          return iterable_fancy_indexing(indexable, request)