code: def test_return_norm_zero_vector_gensim_sparse(self):
      input_vector = []
      return_value = matutils.unitvec(input_vector, return_norm=True)
      self.assertTrue(isinstance(return_value, tuple))
      norm = return_value[1]
      self.assertTrue(isinstance(norm, float))
      self.assertEqual(norm, 1.0)
  
imports: import logging
  import unittest
  import numpy
  from numpy.testing import assert_array_equal
  from scipy import sparse
  from scipy.sparse import csc_matrix
  from scipy.special import psi
  import gensim.matutils
label_desc: Use image node_id 15 for calling the UnitvecTestCase obj's underlying member method code with example usage: obj.test_return_norm_zero_vector_gensim_sparse() without return types