code: def test_b_init(self):
      w_init = initializers.Constant(3)
      b_init = initializers.Constant(4)
      mha1 = attention.MultiHeadAttention(
          2, 3, w_init=w_init, b_init=b_init
      )
      self.assertIs(mha1.b_init, b_init)
  
file_path: dm-haiku/haiku/_src/attention_test.py
imports: from absl.testing import absltest
  from absl.testing import parameterized
  from haiku._src import attention
  from haiku._src import initializers
  from haiku._src import test_utils
  from haiku._src import transform
  import jax
  import jax.numpy
label_desc: Use image node_id 8 for calling the MultiHeadAttentionTest obj's underlying member method code with example usage: obj.test_b_init() without return types