code: def test_cg_without_pytree_equality(self):
      @register_pytree_node_class
      class MinimalPytree:
          def __init__(self, value):
              self.value = value
  
          def tree_flatten(self):
              return [self.value], None
  
          @classmethod
          def tree_unflatten(cls, aux_data, children):
              return cls(*children)
  
      A = lambda x: MinimalPytree(2 * x.value)
      b = MinimalPytree(jnp.arange(5.0))
      expected = b.value / 2
      actual, _ = jax.scipy.sparse.linalg.cg(A, b)
      self.assertAllClose(expected, actual.value)
  
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 8 for calling the LaxBackedScipyTests obj's underlying member method code with example usage: obj.test_cg_without_pytree_equality() and returns: list,  None, cls