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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def append_flipped_images(self):
 """Only flip boxes coordinates, images will be flipped when loading into network"""

        logger.info('%s append flipped images to roidb' % self._name)
        roidb_flipped = []
        for roi_rec in self._roidb:
            boxes = roi_rec['boxes'].copy()
            oldx1 = boxes[:, 0].copy()
            oldx2 = boxes[:, 2].copy()
            boxes[:, 0] = roi_rec['width'] - oldx2 - 1
            boxes[:, 2] = roi_rec['width'] - oldx1 - 1
            assert (boxes[:, 2] >= boxes[:, 0]).all()
            roi_rec_flipped = roi_rec.copy()
            roi_rec_flipped['boxes'] = boxes
            roi_rec_flipped['flipped'] = True
            roidb_flipped.append(roi_rec_flipped)
        self._roidb.extend(roidb_flipped)