code: def test_threads(num_threads):
      # not testing if we use multiple threads
      # just checking if the API throws an exception
      img = 23 * np.ones((100, 100), dtype=np.uint8)
      rolling_ball(img, radius=10, num_threads=num_threads)
      rolling_ball(
          img, radius=10, nansafe=True, num_threads=num_threads
      )
  
file_path: scikit-image/skimage/restoration/tests/test_rolling_ball.py
imports: import numpy
  import pytest
  from skimage import data
  from skimage.restoration._rolling_ball import rolling_ball
  from skimage.restoration._rolling_ball import ellipsoid_kernel
label_desc: Use image node_id 7 for calling a global function with example usage: test_threads(num_threads) without return types