code: def test_unlist_relist_streamlines(rng):
      streamlines = [
          rng.random((10, 3)),
          rng.random((20, 3)),
          rng.random((5, 3)),
      ]
      points, offsets = unlist_streamlines(streamlines)
      assert_equal(offsets.dtype, np.dtype("i8"))
      assert_equal(points.shape, (35, 3))
      assert_equal(len(offsets), len(streamlines))
  
      streamlines2 = relist_streamlines(points, offsets)
      assert_equal(len(streamlines), len(streamlines2))
      for i in range(len(streamlines)):
          assert_array_equal(streamlines[i], streamlines2[i])
  
imports: import warnings
  import types
  import numpy
  from numpy.linalg import norm
  import numpy.testing
  from dipy.testing.memory import get_type_refcount
  from dipy.testing import assert_arrays_equal
  from dipy.testing.decorators import set_random_number_generator
  from dipy.testing import assert_true
  from numpy.testing import assert_array_equal, assert_array_almost_equal, assert_raises, assert_allclose, assert_almost_equal, assert_equal
  from dipy.tracking.streamlinespeed import compress_streamlines, length, set_number_of_points
  from dipy.tracking.streamline import Streamlines
  from dipy.tracking.streamline import relist_streamlines, unlist_streamlines, center_streamlines, transform_streamlines, select_random_set_of_streamlines, select_by_rois, orient_by_rois, orient_by_streamline, values_from_volume, deform_streamlines, cluster_confidence
label_desc: Use image node_id 7 for calling a global function with example usage: test_unlist_relist_streamlines(rng) without return types