code: def test_func_smooth():
      func = load_image(funcfile)
      smoother = LinearFilter(func.coordmap, func.shape)
      # should work, but currently broken : sfunc = smoother.smooth(func)
      pytest.raises(NotImplementedError, smoother.smooth, func)
  
file_path: nipy/nipy/algorithms/tests/test_kernel_smooth.py
imports: import numpy
  import pytest
  from numpy.random import randint
  from numpy.testing import assert_array_almost_equal
  from transforms3d.taitbryan import euler2mat
  from ...None import load_image
  from ...core.api import AffineTransform, Image, compose, drop_io_dim
  from ...testing import anatfile, funcfile
  from ..kernel_smooth import LinearFilter, fwhm2sigma, sigma2fwhm
label_desc: Use image node_id 3 for calling a global function with example usage: test_func_smooth() without return types