code: def test_definition(self):
      for n in [16, 17, 64, 127]:
          x = arange(n) * 2 * pi / n
          y = hilbert(sin(x))
          y1 = direct_hilbert(sin(x))
          assert_array_almost_equal(y, y1)
          assert_array_almost_equal(
              hilbert(sin(2 * x)), direct_hilbert(sin(2 * x))
          )
  
imports: from numpy.testing import assert_equal, assert_almost_equal, assert_array_almost_equal
  from scipy.fftpack import diff, fft, ifft, tilbert, itilbert, hilbert, ihilbert, shift, fftfreq, cs_diff, sc_diff, ss_diff, cc_diff
  import numpy
  from numpy import arange, sin, cos, pi, exp, tanh, sum, sign
  from numpy.random import random
label_desc: Use image node_id 1 for calling the TestHilbert obj's underlying member method code with example usage: obj.test_definition() without return types