code: def test_cg_pytree(self):
      A = lambda x: {
          "a": x["a"] + 0.5 * x["b"],
          "b": 0.5 * x["a"] + x["b"],
      }
      b = {"a": 1.0, "b": -4.0}
      expected = {"a": 4.0, "b": -6.0}
      actual, _ = jax.scipy.sparse.linalg.cg(A, b)
      self.assertEqual(expected.keys(), actual.keys())
      self.assertAlmostEqual(expected["a"], actual["a"], places=6)
      self.assertAlmostEqual(expected["b"], actual["b"], places=6)
  
imports: from functools import partial
  import unittest
  from absl.testing import absltest
  import numpy
  import scipy.sparse.linalg
  import jax
  import jax.numpy
  import jax.scipy.sparse.linalg
  from jax import jit
  from jax import lax
  from jax.tree_util import register_pytree_node_class
  import jax._src.scipy.sparse.linalg
  from jax._src import config
  from jax._src import dtypes
  from jax._src import test_util
label_desc: Use image node_id 5 for calling the LaxBackedScipyTests obj's underlying member method code with example usage: obj.test_cg_pytree() without return types