code: def diff(self):
      texts = []
      for old_path, (new_path, old_l, new_l) in self.change_dct.items():
          if old_path:
              udiff = difflib.unified_diff(old_l, new_l)
          else:
              udiff = difflib.unified_diff(
                  old_l, new_l, old_path, new_path
              )
          texts.append("\n".join(udiff))
      return "\n".join(texts)
  
file_path: catboost/contrib/python/jedi/py3/jedi/refactoring.py
imports: import difflib
  from parso import python_bytes_to_unicode, split_lines
  from jedi.evaluate import helpers
label_desc: Use image node_id 4 for calling the Refactoring obj's underlying member method code with example usage: obj.diff() and returns: str