Relax serializer input restriction to any tuple

Author: cdebost

README.md

@@ -86,8 +86,8 @@ data = {
     'name': 'John Doe',
     'favorite_number': 6
 }
-producer.send('my-topic', value=DataAndSchema(data, schema))
-# the value MUST be an instance of DataAndSchema when we're using the SchemaRegistrySerializer
+producer.send('my-topic', value=(data, schema))
+# the value MUST be a tuple when we're using the SchemaRegistrySerializer
 ```
 
 Read Kafka messages with `SchemaRegistryDeserializer`:
@@ -115,8 +115,11 @@ consumer = KafkaConsumer('my-topic', value_deserializer=deserializer)
 for message in consumer:
     # The deserializer produces DataAndSchema instances
     value: DataAndSchema = message.value
-    value.data
-    value.schema
+    # which are NamedTuples with a `data` and `schema` property
+    value.data == value[0]
+    value.schema == value[1]
+    # and can be deconstructed
+    data, schema = value
 ```
 
 ## Contributing

src/aws_schema_registry/serde.py

@@ -26,7 +26,7 @@
 class DataAndSchema(NamedTuple):
     """Data and its schema.
 
-    Should be used to wrap the data and schema together before calling the
+    Can be used to wrap the data and schema together before calling the
     producer's producing methods.
     """
     data: Any
@@ -74,9 +74,9 @@ def __init__(
     def serialize(self, topic: str, data_and_schema: DataAndSchema):
         if data_and_schema is None:
             return None
-        if not isinstance(data_and_schema, DataAndSchema):
+        if not isinstance(data_and_schema, tuple):
             raise TypeError('AvroSerializer can only serialize',
-                            f' {DataAndSchema}, got {type(data_and_schema)}')
+                            f' {tuple}, got {type(data_and_schema)}')
         data, schema = data_and_schema
         schema_version = self._get_schema_version(topic, schema)
         serialized = schema.write(data)