docs: def load(self):
          """
          Load this step's result from its dump directory
          """
          hdf_filename = os.path.join(self._dump_dirname, 'result.h5')
          if os.path.isfile(hdf_filename):
              store = pd.HDFStore(hdf_filename, mode='r')
              keys = store.keys()
              if keys == ['/df']:
                  self.result = store['df']
              else:
                  if set(keys) == set(map(lambda i: '/%s' % i, range(len(keys)))):
                      # keys are not necessarily ordered
                      self.result = [store[str(k)] for k in range(len(keys))]
                  else:
                      self.result = {k[1:]: store[k] for k in keys}
  
          else:
              self.result = joblib.load(
                      os.path.join(self._output_dirname, 'dump', 'result.pkl'))