code: func (conn *BytesConnectionStr) SendAsyncByte(topic string, key []byte, value []byte, meta interface{}, successClb func(*client.ProducerMessage), errClb func(*client.ProducerError)) {
  	conn.SendAsyncMessage(topic, sarama.ByteEncoder(key), sarama.ByteEncoder(value), meta, successClb, errClb)
  }
docs: // SendAsyncByte sends a message that uses byte encoder using the async API