docs: def get_overlay(self):
          """
          Function make 3D data from dicom file slices. There are usualy
          more overlays in the data.
          """
          overlay = {}
          dcmlist = self.files_in_serie
  
          for i in range(len(dcmlist)):
              onefile = dcmlist[i]
              logger.info("reading '%s'" % onefile)
              data = self._read_file(onefile)
  
              if len(overlay) == 0:
                  # first there is created dictionary with
                  # avalible overlay indexes
                  for i_overlay in range(0, 50):
                      try:
                          # overlay index
                          data2d = decode_overlay_slice(data, i_overlay)
                          # mport pdb; pdb.set_trace()
                          shp2 = data2d.shape
                          overlay[i_overlay] = np.zeros([len(dcmlist), shp2[0],
                                                         shp2[1]], dtype=np.int8)
                          overlay[i_overlay][-i - 1, :, :] = data2d
  
                      except Exception:
                          # exception is exceptetd. We are trying numbers 0-50
                          # logger.exception('Problem with overlay image number ' +
                          #               str(i_overlay))
                          pass
  
              else:
                  for i_overlay in overlay.keys():
                      try:
                          data2d = decode_overlay_slice(data, i_overlay)
                          overlay[i_overlay][-i - 1, :, :] = data2d
                      except Exception:
                          logger.warning('Problem with overlay number ' +
                                         str(i_overlay))
  
          return overlay