code: def filename(self) -> str:
          
          if self._new_path is not None and str(self._new_path) != "/dev/null":
              path = self._new_path
          else:
              path = self._old_path
  
          return path.name
docs: Return the filename. Given a path-like-string (e.g.
          "/Users/dspadini/pydriller/myfile.py") returns only the filename
          (e.g. "myfile.py")
  
          :return: str filename