code: def to_str(self, obj):
      return "".join(str(obj).split())
  
imports: import sys
  import qlib
  import shutil
  import unittest
  import pytest
  import pandas
  import baostock
  from pathlib import Path
  from qlib.data import D
  from qlib.tests.data import GetData
  from dump_pit import DumpPitData
  from collector import Run
label_desc: Use image node_id 4 for calling the TestPIT obj's underlying member method code with example usage: obj.to_str(obj) and returns: str