code: def test_connectivity_matrix_shape():
      # Labels: z-planes have labels 0,1,2
      labels = np.zeros((3, 3, 3), dtype=int)
      labels[:, :, 1] = 1
      labels[:, :, 2] = 2
      # Streamline set, only moves between first two z-planes.
      streamlines = [
          np.array([[0.0, 0.0, 0.0], [0.0, 0.0, 0.5], [0.0, 0.0, 1.0]]),
          np.array([[0.0, 1.0, 1.0], [0.0, 1.0, 0.5], [0.0, 1.0, 0.0]]),
      ]
      matrix = connectivity_matrix(streamlines, np.eye(4), labels)
      npt.assert_equal(matrix.shape, (3, 3))
  
imports: import warnings
  import numpy
  import pytest
  from dipy.tracking import metrics
  from dipy.tracking.streamline import transform_streamlines
  from dipy.tracking.utils import connectivity_matrix, density_map, length, ndbincount, reduce_labels, seeds_from_mask, random_seeds_from_mask, target, target_line_based, unique_rows, near_roi, reduce_rois, path_length, _min_at, max_angle_from_curvature, min_radius_curvature_from_angle
  from dipy.tracking._utils import _to_voxel_coordinates
  from dipy.tracking.vox2track import streamline_mapping
  import numpy.testing
  from dipy.testing import assert_true
  from dipy.testing.decorators import set_random_number_generator
label_desc: Use image node_id 16 for calling a global function with example usage: test_connectivity_matrix_shape() without return types