code: def _get_kernel_fn(self, same_inputs, readin, readout):
      key = random.PRNGKey(1)
      x1 = random.normal(key, (2, 5, 6, 3))
      x2 = None if same_inputs else random.normal(key, (3, 5, 6, 3))
      layers = [readin]
      filter_shape = (2, 3) if readin[0].__name__ == "Identity" else ()
      layers += [
          stax.Conv(1, filter_shape, padding="SAME"),
          stax.Relu(),
          stax.Conv(1, filter_shape, padding="SAME"),
          stax.Erf(),
          readout,
      ]
      _, _, kernel_fn = stax.serial(*layers)
      return kernel_fn, x1, x2
  
imports: import itertools
  import random
  from absl.testing import absltest
  from jax import config
  from jax import default_backend
  from jax import jit
  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 1 for calling the DiagonalTest obj's underlying member method code with example usage: obj._get_kernel_fn(same_inputs, readin, readout) and returns: kernel_fn,  x1,  x2