code: def output(self):
          
          subts = [s.output for s in self.sims]
          sub_ndim = subts[0].ndim
          if sub_ndim is 1:
              subts = [distob.expand_dims(ts, 1) for ts in subts]
              sub_ndim += 1
          nodeaxis = sub_ndim
          subts = [distob.expand_dims(ts, nodeaxis) for ts in subts]
          ts = subts[0].concatenate(subts[1:], axis=nodeaxis)
          ts.labels[nodeaxis] = self._node_labels()
          return ts
docs: Rank 3 array representing output time series. Axis 0 is time, 
          axis 1 ranges across output variables of a single simulation, 
          axis 2 ranges across different simulation instances.