code: def test_curvature_angle():
      angle = [0.0000001, np.pi / 3, np.pi / 2.01]
      step_size = [0.2, 0.5, 1.5]
      curvature = [2000000.0, 0.5, 1.064829060280437]
  
      for theta, step, curve in zip(angle, step_size, curvature):
          res_angle = max_angle_from_curvature(curve, step)
          npt.assert_almost_equal(res_angle, theta)
  
          res_curvature = min_radius_curvature_from_angle(theta, step)
          npt.assert_almost_equal(res_curvature, curve)
  
      # special case
      with pytest.warns(UserWarning):
          npt.assert_equal(
              min_radius_curvature_from_angle(0, 1),
              min_radius_curvature_from_angle(np.pi / 2, 1),
          )
  
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 21 for calling a global function with example usage: test_curvature_angle() without return types