code: def test_gradient(self):
      rng = np.random.RandomState(43)
  
      def output_0(x, y):
          return self.op_class()(x, y)[0]
  
      def output_1(x, y):
          return self.op_class()(x, y)[1]
  
      utt.verify_grad(
          output_0,
          [rng.random((5, 4)), rng.random((5, 4))],
          n_tests=1,
          rng=TestSumDiffOp.rng,
      )
      utt.verify_grad(
          output_1,
          [rng.random((5, 4)), rng.random((5, 4))],
          n_tests=1,
          rng=TestSumDiffOp.rng,
      )
  
imports: import unittest
  import pytensor
  from pytensor.graph.basic import Apply
  from pytensor.graph.op import Op
  from pytensor.tensor.type import TensorType
  from tests import unittest_tools
  from pytensor import tensor
  from pytensor.graph.basic import Apply
  from pytensor.tensor.type import dmatrix, matrix
  import numpy
  import pytensor
  from pytensor.compile.ops import as_op
label_desc: Use image node_id 3 for calling the TestSumDiffOp obj's underlying member method code with example usage: obj.test_gradient() and returns: self, self