code: def test_kernel_input():
      """Test the kernel for inputs of type Sphere, type int and for input None"""
  
      sph = Sphere(1, 0, 0)
      D33 = 1.0
      D44 = 0.04
      t = 1
      k = EnhancementKernel(
          D33, D44, t, orientations=sph, force_recompute=True
      )
      npt.assert_equal(k.get_lookup_table().shape, (1, 1, 7, 7, 7))
  
      num_orientations = 2
      k = EnhancementKernel(
          D33,
          D44,
          t,
          orientations=num_orientations,
          force_recompute=True,
      )
      npt.assert_equal(k.get_lookup_table().shape, (2, 2, 7, 7, 7))
  
      k = EnhancementKernel(
          D33, D44, t, orientations=0, force_recompute=True
      )
      npt.assert_equal(k.get_lookup_table().shape, (0, 0, 7, 7, 7))
  
file_path: dipy/dipy/denoise/tests/test_kernel.py
imports: import warnings
  from dipy.denoise.enhancement_kernel import EnhancementKernel
  from dipy.denoise.shift_twist_convolution import convolve, convolve_sf
  from dipy.reconst.shm import sh_to_sf, sf_to_sh, descoteaux07_legacy_msg
  from dipy.core.sphere import Sphere
  import numpy
  import numpy.testing
label_desc: Use image node_id 4 for calling a global function with example usage: test_kernel_input() without return types