def METHOD_NAME(self):
    '''
    Returns category names of VOC dataset classes.
    '''
    if hasattr(self, '_category_names'):
        return self._category_names
    voc_dir = os.path.join(os.path.dirname(__file__))
    voc_dir = os.path.join(voc_dir.replace('semantic_segmentation', 'object_detection'),
                           'voc.names')
    with open(voc_dir, 'r') as fd:
        self._category_names = fd.read().splitlines()
    return self._category_names