code: def get_example(self, i):
      img = np.random.randint(0, 256, size=(3, 48, 64))
      label = np.random.randint(-1, 21, size=(48, 64)).astype(np.int32)
  
      return (img, label) + self.options
  
imports: import numpy
  import unittest
  from chainer.dataset import DatasetMixin
  from chainercv.utils import assert_is_semantic_segmentation_dataset
  from chainercv.utils import testing
label_desc: Use image node_id 3 for calling the SemanticSegmentationDataset obj's underlying member method code with example usage: obj.get_example(i) and returns: unknown