code: def test_NW_simple_laplacian_kernel():
      X = np.arange(11.0)
      y = X + 1
      dy = 1
  
      # by symmetry, NW regression should get these exactly correct
      Xfit = np.array([4, 5, 6])[:, None]
      y_true = np.ravel(Xfit + 1)
  
      kwargs = {"gamma": 10.0}
      clf = NadarayaWatson(kernel="laplacian", **kwargs).fit(
          X[:, None], y, dy
      )
      y_fit = clf.predict(Xfit)
  
      assert_allclose(y_fit, y_true)
  
imports: import numpy
  from numpy.testing import assert_allclose
  import pytest
  from astroML.linear_model import NadarayaWatson
label_desc: Use image node_id 2 for calling a global function with example usage: test_NW_simple_laplacian_kernel() without return types