import tensorflow as tf

                         [1, 1]], dtype=tf.float32)
    mask4 = tf.constant([[0, 0],
                         [0, 0]], dtype=tf.float32)
    mask5 = tf.constant([[1, 0],
                         [1, 0]], dtype=tf.float32)
    masks1 = tf.stack([mask0, mask1, mask2])
    masks2 = tf.stack([mask3, mask4, mask5])
    ious = isu.get_pairwise_iou_matrix(masks1, masks2)
    expected_ious = tf.constant([[0.5, 0.0, 1.0/3.0],
                                 [0.75, 0.0, 0.25],
