# File lib/Dnsruby/message.rb, line 770
    def Header.decrement_arcount_encoded(bytes)
      header = Header.new
      header_end = 0
      MessageDecoder.new(bytes) {|msg|
        header.decode(msg)
        header_end = msg.index
      }
      header.arcount = header.arcount - 1
      bytes[0,header_end]=MessageEncoder.new {|msg|
        header.encode(msg)}.to_s
      return bytes
    end