elif act == 'TANH':
    y = math_ops.conj(y)
    grad = gen_math_ops.tanh_grad(y, grad)

  broadcast_shape = tf.shape(y)
  input_value_shape = tf.shape(op.inputs[2])
  _, reduction_axes = tf.raw_ops.BroadcastGradientArgs(
      s0=broadcast_shape, s1=input_value_shape)
  updates_grad_reshaped = tf.reduce_sum(
      grad, axis=reduction_axes, keepdims=True)
  bias_grad = tf.reshape(updates_grad_reshaped, input_value_shape)