code: def test_structural_similarity_dtype(dtype):
      N = 30
      X = np.random.rand(N, N)
      Y = np.random.rand(N, N)
      if np.dtype(dtype).kind in "iub":
          data_range = 255.0
          X = (X * 255).astype(np.uint8)
          Y = (X * 255).astype(np.uint8)
      else:
          data_range = 1.0
          X = X.astype(dtype, copy=False)
          Y = Y.astype(dtype, copy=False)
  
      S1 = structural_similarity(X, Y, data_range=data_range)
      assert S1.dtype == np.float64
  
      assert S1 < 0.1
  
file_path: scikit-image/skimage/metrics/tests/test_structural_similarity.py
imports: import numpy
  import pytest
  from numpy.testing import assert_equal, assert_almost_equal
  from skimage import data
  from skimage._shared._warnings import expected_warnings
  from skimage._shared.utils import _supported_float_type
  from skimage.metrics import structural_similarity
label_desc: Use image node_id 4 for calling a global function with example usage: test_structural_similarity_dtype(dtype) without return types