def tf__huber_loss(a):
  with tf.name_scope('huber_loss'):

    def if_true():
      with tf.name_scope('if_true'):
        loss = a * a / 2
        return loss,

    def if_false():
      with tf.name_scope('if_false'):
        loss = delta * (tf.abs(a) - delta / 2)
        return loss,
    loss = ag__.utils.run_cond(tf.less_equal(tf.abs(a), delta), if_true,
        if_false)
    return loss