class_docstr: Segmentation Base Dataset
class_docstr_tok: ["Segmentation","Base","Dataset"]
docstr: Number of categories.
docstr_tok: ["Number","of","categories","."]
code: def num_class(self):
      """Number of categories."""
      return self.NUM_CLASS
  
file_path: gluon-cv/gluoncv/data/segbase.py
imports: import random
  import numpy
  from PIL import Image, ImageOps, ImageFilter
  import mxnet
  from mxnet import cpu
  import mxnet.ndarray
  from .base import VisionDataset
label_desc: Use image node_id 6 for calling the SegmentationDataset obj's underlying member method code with example usage: obj.num_class() and returns: self