class_docstr: Test for tri-diagonal matrix related ops.
code: def testGradientSimple(self):
      self._gradientTest(
          diags=_sample_diags,
          rhs=_sample_rhs,
          y=[1, 3, 2, 4],
          expected_grad_diags=[
              [-5, 0, 4, 0],
              [9, 0, -4, -16],
              [0, 0, 5, 16],
          ],
          expected_grad_rhs=[1, 0, -1, 4],
      )
  
imports: import numpy
  from tensorflow.compiler.tests import xla_test
  from tensorflow.python.framework import constant_op
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import errors_impl
  from tensorflow.python.framework import test_util
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import gradients
  from tensorflow.python.ops import math_ops
  from tensorflow.python.ops.linalg import linalg_impl
  from tensorflow.python.platform import test
label_desc: Use image node_id 31 for calling the TridiagonalSolveOpsTest obj's underlying member method code with example usage: obj.testGradientSimple() without return types