code: def test_mgrid_single_element(self):
      # Ticket #339
      assert_array_equal(np.mgrid[0:0:1j], [0])
      assert_array_equal(np.mgrid[0:0], [])
  
imports: import os
  import numpy
  from numpy.testing import assert_, assert_equal, assert_array_equal, assert_array_almost_equal, assert_raises, _assert_valid_refcount
  import pytest
label_desc: Use image node_id 6 for calling the TestRegression obj's underlying member method code with example usage: obj.test_mgrid_single_element() without return types