code: def convert_background_from_zero_to_last(label_ids, class_map):
      label_ids = label_ids - 1
      label_ids[label_ids == -1] = class_map.num_classes - 1
      return label_ids
  
file_path: icevision/icevision/models/mmseg/common/utils.py
imports: from icevision.imports import *
  from icevision.utils import *
  from mmcv import Config
  from mmseg.apis import init_segmentor
  from mmseg.models import build_segmentor
  from mmcv.runner import load_checkpoint
  from icevision.models.mmseg.utils import *
  from icevision.core.exceptions import *
  from mmcv.cnn.utils import revert_sync_batchnorm
label_desc: Use image node_id 1 for calling a global function with example usage: convert_background_from_zero_to_last(label_ids, class_map) and returns: label_ids