docstr: Simple transfer guard tests.
docstr_tok: ["Simple","transfer","guard","tests","."]
code: def test_simple(self):
      """Simple transfer guard tests."""
      with jax.transfer_guard("allow"):
          with self.assertAllows("host_to_device_jnp_ones"):
              jnp.ones(1)
      with jax.transfer_guard("log"):
          with self.assertLogs("host_to_device_jnp_ones"):
              jnp.ones(1)
      with jax.transfer_guard("disallow"):
          with self.assertDisallows("host_to_device_jnp_ones"):
              jnp.ones(1)
  
imports: import contextlib
  import pickle
  from absl.testing import absltest
  from absl.testing import parameterized
  import numpy
  import jax
  import jax._src.test_util
  import jax.numpy
  from jax import config
label_desc: Use image node_id 4 for calling the TransferGuardTest obj's underlying member method code with example usage: obj.test_simple() without return types