code: def test_phase(self):
      o = specdesc("phase", buf_size)
      spec = cvec(buf_size)
      # phase of zeros is zero
      assert_equal(o(spec), 0.0)
      spec.phas = random.random_sample((len(spec.phas),)).astype(
          float_type
      )
      # phase of random is not zero
      spec.norm[:] = 1
      assert o(spec) != 0.0
  
imports: from numpy.testing import TestCase, assert_equal, assert_almost_equal
  from numpy import random, arange, log, zeros
  from aubio import specdesc, cvec, float_type
label_desc: Use image node_id 2 for calling the aubio_specdesc obj's underlying member method code with example usage: obj.test_phase() without return types