code: def __getattr__(self, key):
      if key == "data_set":
          self._data_set = self._data_set or self.create_data_set()
          self.__dict__["data_set"] = self._data_set
          return self._data_set
      raise AttributeError
  
imports: import argparse
  import cv2
  import numpy
  import nvidia.dali
  import nvidia.dali.types
  import os
label_desc: Use image node_id 2 for calling the SampleLoader obj's underlying member method code with example usage: obj.__getattr__(key) and returns: self