code: def test_union1d(self):
      a = np.array([5, 4, 7, 1, 2])
      b = np.array([2, 4, 3, 3, 2, 1, 5])
  
      ec = np.array([1, 2, 3, 4, 5, 7])
      c = union1d(a, b)
      assert_array_equal(c, ec)
  
      # Tests gh-10340, arguments to union1d should be
      # flattened if they are not already 1D
      x = np.array([[0, 1, 2], [3, 4, 5]])
      y = np.array([0, 1, 2, 3, 4])
      ez = np.array([0, 1, 2, 3, 4, 5])
      z = union1d(x, y)
      assert_array_equal(z, ez)
  
      assert_array_equal([], union1d([], []))
  
imports: from unittest import skipIf
  import numpy
  from pytest import raises
  from torch.testing._internal.common_utils import instantiate_parametrized_tests, parametrize, run_tests, subtest, TEST_WITH_TORCHDYNAMO, TestCase, xpassIfTorchDynamo
label_desc: Use image node_id 25 for calling the TestSetOps obj's underlying member method code with example usage: obj.test_union1d() without return types