new_contents: def unittest(data_path, temp_path):
      import ulinalg
      from vec import distance
      m = ulinalg.ones(1, 10)
      d = distance.euclidean((0, 0, 0), (0, 1, 0))
      return (abs(1.0-d) < 0.01) and (abs(10.0 - sum(m)) < 0.01)
  
subject: Add unit-test to test frozen modules.