code: def test_hough_line_peaks_single_line():
      # Regression test for gh-6187, gh-4129
  
      # create an empty test image
      img = np.zeros((100, 100), dtype=bool)
      # draw a horizontal line into our test image
      img[30, :] = 1
  
      hough_space, angles, dist = transform.hough_line(img)
  
      best_h_space, best_angles, best_dist = transform.hough_line_peaks(
          hough_space, angles, dist
      )
      assert len(best_angles) == 1
      assert len(best_dist) == 1
      expected_angle = -np.pi / 2
      expected_dist = -30
      assert abs(best_angles[0] - expected_angle) < 0.01
      assert abs(best_dist[0] - expected_dist) < 0.01
  
imports: import numpy
  import pytest
  from numpy.testing import assert_almost_equal, assert_equal
  from skimage import data, transform
  from skimage._shared.testing import run_in_parallel
  from skimage.draw import circle_perimeter, ellipse_perimeter, line
label_desc: Use image node_id 9 for calling a global function with example usage: test_hough_line_peaks_single_line() without return types