class_docstr: ADE20K Semantic Segmentation Dataset.
  
  Parameters
  ----------
  root : string
      Path to VOCdevkit folder. Default is '$(HOME)/mxnet/datasplits/ade'
  split: string
      'train', 'val' or 'test'
  transform : callable, optional
      A function that transforms the image
  
  Examples
  --------
  >>> from mxnet.gluon.data.vision import transforms
  >>> # Transforms for Normalization
  >>> input_transform = transforms.Compose([
  >>>     transforms.ToTensor(),
  >>>     transforms.Normalize([.485, .456, .406], [.229, .224, .225]),
  >>> ])
  >>> # Create Dataset
  >>> trainset = gluoncv.data.ADE20KSegmentation(split='train', transform=input_transform)
  >>> # Create Training Loader
  >>> train_data = gluon.data.DataLoader(
  >>>     trainset, 4, shuffle=True, last_batch='rollover',
  >>>     num_workers=4)
code: def _mask_transform(self, mask):
      return mx.nd.array(np.array(mask), mx.cpu(0)).astype("int32") - 1
  
file_path: gluon-cv/gluoncv/data/ade20k/segmentation.py
imports: import os
  from PIL import Image
  import numpy
  import mxnet
  from ..segbase import SegmentationDataset
label_desc: Use image node_id 3 for calling the ADE20KSegmentation obj's underlying member method code with example usage: obj._mask_transform(mask) and returns: unknown