class_docstr: Tests for the MPO losses.
class_docstr_tok: ["Tests","for","the","MPO","losses","."]
docstr: Test if the top k fraction returns 0 advantages we raise an error.
docstr_tok: ["Test","if","the","top","k","fraction","returns","0","advantages","we","raise","an","error","."]
code: def test_top_k_fraction_too_low(self):
      """Test if the top k fraction returns 0 advantages we raise an error."""
      with self.assertRaises(ValueError):
          mpo_ops.get_top_k_weights(
              0.01, jnp.ones((3, 2)), jnp.ones((3, 2))
          )
  
imports: import functools
  import math
  from typing import Tuple
  from absl.testing import absltest
  from absl.testing import parameterized
  import chex
  import haiku
  import jax
  import jax.numpy
  import numpy
  import optax
  from rlax._src import distributions
  from rlax._src import mpo_ops
label_desc: Use image node_id 8 for calling the MPOTest obj's underlying member method code with example usage: obj.test_top_k_fraction_too_low() without return types