code: def __getitem__(self, idx):
      return mx.nd.ones(shape=self.shape) * idx
  
imports: from __future__ import print_function
  from __future__ import division
  import mxnet
  import numpy
  import gluoncv
  from gluoncv.data.batchify import *
  from gluoncv.data import DetectionDataLoader, RandomTransformDataLoader
label_desc: Use image node_id 3 for calling the DummySequentialDataset obj's underlying member method code with example usage: obj.__getitem__(idx) and returns: unknown