code: def samples_by_indices(self, indices):
          
          indices = self.sampler.map_indices(indices)
          return self.samples_by_indices_nomapping(indices)
docs: Gather a batch of samples by indices, applying the mapping
          described by the (optional) `indices` array passed to the
          constructor.
  
          Parameters
          ----------
          indices: 1D-array of ints or slice
              The samples to retrieve
  
          Returns
          -------
          list of arrays
              A mini-batch in the form of a list of NumPy arrays