# File lib/stomp/connection.rb, line 257
    def nack(message_id, headers = {})
      raise Stomp::Error::NoCurrentConnection if closed?
      raise Stomp::Error::UnsupportedProtocolError if @protocol == Stomp::SPL_10
      raise Stomp::Error::MessageIDRequiredError if message_id.nil? || message_id == ""
      headers = headers.symbolize_keys
      headers['message-id''message-id'] = message_id
      raise Stomp::Error::SubscriptionRequiredError unless headers[:subscription]
      _headerCheck(headers)
      transmit(Stomp::CMD_NACK, headers)
    end