code: def test_nonlineariy(self, phi, same_inputs, a, b, n):
      width = 2**10
      n_samples = 2**9
      init_fn, apply_fn, kernel_fn = stax.serial(
          stax.Dense(width),
          phi(a=a, b=b),
          stax.Dense(width),
          phi(a=a, b=b),
          stax.Dense(1),
      )
  
      key1, key2, key_mc = random.split(random.PRNGKey(1), 3)
      shape = (4, 3, 2)[:n] + (1,)
      x1 = jnp.cos(random.normal(key1, (2,) + shape))
      if same_inputs is None:
          x2 = None
      elif same_inputs is True:
          x2 = x1
      else:
          x2 = jnp.cos(random.normal(key2, (3,) + shape))
  
      k = kernel_fn(x1, x2)
      mc_kernel_fn = nt.monte_carlo_kernel_fn(
          init_fn, apply_fn, key_mc, n_samples
      )
      k_mc = mc_kernel_fn(x1, x2, ("nngp", "ntk"))
      test_utils.assert_close_matrices(self, k_mc.nngp, k.nngp, 6e-2)
      test_utils.assert_close_matrices(self, k_mc.ntk, k.ntk, 6e-2)
  
imports: import itertools
  import random
  from absl.testing import absltest
  from jax import config
  from jax import default_backend
  from jax import grad, jacfwd, jacrev, jit, jvp, value_and_grad
  from jax import random
  import jax.numpy
  import neural_tangents
  from neural_tangents import stax
  from neural_tangents._src.empirical import _DEFAULT_TESTING_NTK_IMPLEMENTATION
  from tests import test_utils
label_desc: Use image node_id 9 for calling the ActivationTest obj's underlying member method code with example usage: obj.test_nonlineariy(phi, same_inputs, a, b, n) without return types