code: def test_constant_image(self):
      image = np.full((20, 20), 128, dtype=np.uint8)
      peaks = peak.peak_local_max(image, min_distance=1)
      assert len(peaks) == 0
  
imports: import itertools
  import numpy
  import pytest
  from numpy.testing import assert_array_almost_equal, assert_array_equal, assert_equal
  from scipy import ndimage
  from skimage._shared._warnings import expected_warnings
  from skimage.feature import peak
label_desc: Use image node_id 5 for calling the TestPeakLocalMax obj's underlying member method code with example usage: obj.test_constant_image() without return types