code: def _PromptUserForAPFSVolumeIdentifiers(
        self, volume_system, volume_identifiers):
      
      print_header = True
      while True:
        if print_header:
          self._PrintAPFSVolumeIdentifiersOverview(
              volume_system, volume_identifiers)
  
          print_header = False
  
        lines = self._textwrapper.wrap(self._USER_PROMPT_APFS)
        self._output_writer.Write('\n'.join(lines))
        self._output_writer.Write('\n\nVolume identifiers: ')
  
        try:
          selected_volumes = self._ReadSelectedVolumes(
              volume_system, prefix='apfs')
          if (not selected_volumes or
              not set(selected_volumes).difference(volume_identifiers)):
            break
        except ValueError:
          pass
  
        self._output_writer.Write('\n')
  
        lines = self._textwrapper.wrap(
            'Unsupported volume identifier(s), please try again or abort with '
            'Ctrl^C.')
        self._output_writer.Write('\n'.join(lines))
        self._output_writer.Write('\n\n')
  
      return selected_volumes
docs: Prompts the user to provide APFS volume identifiers.
  
      Args:
        volume_system (dfvfs.APFSVolumeSystem): volume system.
        volume_identifiers (list[str]): volume identifiers including prefix.
  
      Returns:
        list[str]: selected volume identifiers including prefix or None.