code: def testUtilityNorm(self):
      x0 = (jnp.ones(2), (jnp.ones(3), jnp.ones(4)))
      norm = optimizers.l2_norm(x0)
      expected = np.sqrt(np.sum(np.ones(2 + 3 + 4) ** 2))
      self.assertAllClose(norm, expected, check_dtypes=False)
  
imports: import functools
  from absl.testing import absltest
  import numpy
  import jax.numpy
  import jax._src.test_util
  from jax import jit, grad, jacfwd, jacrev
  from jax import tree_util
  from jax import lax
  from jax.example_libraries import optimizers
  from jax import config
label_desc: Use image node_id 24 for calling the OptimizerTests obj's underlying member method code with example usage: obj.testUtilityNorm() without return types