code: def update_parent_directory_number(self, parent_dir_num):
          # type: (int) -> None
          '''
          A method to update the parent directory number for this Path Table
          Record from the directory record.
  
          Parameters:
           parent_dir_num - The new parent directory number to assign to this PTR.
          Returns:
           Nothing.
          '''
          if not self._initialized:
              raise pycdlibexception.PyCdlibInternalError('Path Table Record not yet initialized')
          self.parent_directory_num = parent_dir_nuf update_parent_directory_number(self, parent_dir_num):
          # type: (int) -> None
          '''
          A method to update the parent directory number for this Path Table
          Record from the directory record.
  
          Parameters:
           parent_dir_num - The new parent directory number to assign to this PTR.
          Returns:
           Nothing.
          '''
          if not self._initialized:
              raise pycdlibexception.PyCdlibInternalError('Path Table Record not yet initialized')
          self.parent_directory_num = parent_dir_num
docs: A method to update the parent directory number for this Path Table
          Record from the directory record.
  
          Parameters:
           parent_dir_num - The new parent directory number to assign to this PTR.
          Returns:
           Nothing.