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  def end_of_message(context)
    @encoding ||= nil
    nkf_option = "-w"
    nkf_option << " -MB" if @encoding == "base64"
    body = @values["body"]
    @values["body"] = NKF.nkf(nkf_option, body)
    messages = Groonga["Messages"]
    messages.add(@values)
  end