code: def BenesBlock(d_model, dropout, mode):
      def bit_sequence(inputs):
          seq_length = inputs.shape[1]
          n_bits = np.int32(np.log(seq_length - 1) / np.log(2.0)) + 1
          return jnp.arange(0, n_bits)
  
      return tl.Serial(
          tl.Dup(),
          tl.Fn("BitSeq", bit_sequence, n_out=1),
          tl.Scan(_ForwardStep(d_model, dropout, mode)),
          tl.Scan(_BackwardStep(d_model, dropout, mode)),
          tl.Select([1]),
      )
  
imports: import numpy
  from trax import fastmath
  from trax import layers
  from trax.fastmath import numpy
  from trax.layers.assert_shape import assert_shape
label_desc: Use image node_id 10 for calling a global function with example usage: BenesBlock(d_model, dropout, mode) and returns: tl, jnp