code: def value_net(rng_key,
                batch_observations_shape,
                num_actions,
                bottom_layers=None):
    
    del num_actions
  
    if bottom_layers is None:
      bottom_layers = []
    bottom_layers.extend([
        layers.Dense(1),
    ])
    net = layers.Serial(*bottom_layers)
    return net.initialize(batch_observations_shape, rng_key), net
docs: A value net function.