class_docstr: Desc: Data preprocessing,
code: def get_raw_df(self):
      return self.raw_df
  
imports: import os
  import time
  import datetime
  import numpy
  import pandas
  import paddle
  from paddle.io import Dataset
  import pgl
  from pgl.utils.logger import log
label_desc: Use image node_id 4 for calling the TestPGL4WPFDataset obj's underlying member method code with example usage: obj.get_raw_df() and returns: self