我正在使用python3和合流python向kafka发送消息。我需要用avro格式的值和字符串形式的键发送数据。但是我发现合流的python只能以avro或字符串的形式发送这两个文件。融合的python源代码如下：

def produce(self,**kwargs):
    """
        Asynchronously sends a message to Kafka by encoding with specified or default Avro schema.

        :param str topic: topic name
        :param object value: An object to serialize
        :param str value_schema: Avro schema for value
        :param object key: An object to serialize
        :param str key_schema: Avro schema for key

        Plus any other parameters accepted by confluent_kafka.Producer.produce

        :raises SerializerError: On serialization failure
        :raises BufferError: If producer queue is full.
        :raises KafkaException: For other produce failures.
    """
    # get schemas from  kwargs if defined
    key_schema = kwargs.pop('key_schema', self._key_schema)
    value_schema = kwargs.pop('value_schema', self._value_schema)
    topic = kwargs.pop('topic', None)
    if not topic:
        raise ClientError("Topic name not specified.")
    value = kwargs.pop('value', None)
    key = kwargs.pop('key', None)

    if value is not None:
        if value_schema:
            value = self._serializer.encode_record_with_schema(topic, value_schema, value)
        else:
            raise ValueSerializerError("Avro schema required for values")

    if key is not None:
        if key_schema:
            key = self._serializer.encode_record_with_schema(topic, key_schema, key, True)
        else:
            raise KeySerializerError("Avro schema required for key")

    super(AvroProducer, self).produce(topic, value, key,**kwargs)

有人知道吗？