def _concat_bbox(bbox, bboxes):
    """Helper function that concates bbox to bboxes along the first dimension."""

    # Note if all elements in bboxes are -1 (_INVALID_BOX), then this means
    # we discard bboxes and start the bboxes Tensor with the current bbox.
    bboxes_sum_check = np.sum(bboxes)
    bbox = np.expand_dims(bbox, 0)
    # This check will be true when it is an _INVALID_BOX
    if _equal(bboxes_sum_check, -4):
        bboxes = bbox
    else:
        bboxes = np.concatenate([bboxes, bbox], 0)
    return bboxes
Helper function that concates bbox to bboxes along the first dimension.
ppdet/data/transform/autoaugment_utils.py