def dump(record)
      data =
        if record.size == 1
          [record[0].bytesize, DELETE].pack('NN') << record[0]
        else
          [record[0].bytesize, record[1].bytesize].pack('NN') << record[0] << record[1]
        end
      data << crc32(data)
    end
def dump(record)
      data =
        if record.size == 1
          [record[0].bytesize, DELETE].pack('NN') << record[0]
        else
          [record[0].bytesize, record[1].bytesize].pack('NN') << record[0] << record[1]
        end
      data << crc32(data)
    end
Serialize record and return string
 @param [Array] record an array with [key, value] or [key] if the record is deleted
 @return [String] serialized record