with tf.name_scope(scope, 'PruneNonOverlappingBoxes'):
    ioa_ = ioa(boxlist2, boxlist1)  # [M, N] tensor
    ioa_ = tf.reduce_max(ioa_, reduction_indices=[0])  # [N] tensor
    keep_bool = tf.greater_equal(ioa_, tf.constant(min_overlap))
    keep_inds = tf.squeeze(tf.where(keep_bool), axis=[1])