code: def test_get_policy(self):
      self.assertIsNone(mixed_precision.get_policy(InnerModule))
      policy = jmp.get_policy("p=f16,c=f32,o=f16")
      mixed_precision.set_policy(InnerModule, policy)
      self.assertEqual(mixed_precision.get_policy(InnerModule), policy)
      mixed_precision.clear_policy(InnerModule)
      self.assertIsNone(mixed_precision.get_policy(InnerModule))
  
imports: import importlib
  from typing import Optional
  from absl.testing import absltest
  from haiku._src import base
  from haiku._src import conv
  from haiku._src import mixed_precision
  from haiku._src import module
  from haiku._src import test_utils
  from haiku._src import transform
  import jax
  import jax.numpy
  import jmp
label_desc: Use image node_id 1 for calling the MixedPrecisionTest obj's underlying member method code with example usage: obj.test_get_policy() without return types