code: def postproc (stats_result):
      
      n, mean, scat = stats_result
      mean *= 180 / np.pi # rad => deg
      scat /= n # variance-of-samples => variance-of-mean
      scat **= 0.5 # variance => stddev
      scat *= 180 / np.pi # rad => deg
      return mean, scat
docs: Simple helper to postprocess angular outputs from StatsCollectors in the
      way we want.