code: def get_example(self, i):
      img, mask, label = super(
          MismatchLabelLengthDataset, self
      ).get_example(i)[:3]
      return img, mask, label[1:]
  
imports: import numpy
  import unittest
  from chainer.dataset import DatasetMixin
  from chainercv.utils import assert_is_instance_segmentation_dataset
  from chainercv.utils import testing
label_desc: Use image node_id 1 for calling the MismatchLabelLengthDataset obj's underlying member method code with example usage: obj.get_example(i) and returns: img,  mask,  label