code: def __call__(self):
      return self.dataset
  
imports: import os
  import copy
  import numpy
  from paddle.io import Dataset
  from ppdet.core.workspace import register, serializable
  from ppdet.utils.download import get_dataset_path
  from ppdet.data import source
  from ppdet.utils.logger import setup_logger
label_desc: Use image node_id 2 for calling the CommonDataset obj's underlying member method code with example usage: obj.__call__() and returns: self