I'd like to be able to write smart serializers, where I can share information whit the invoked sub-serializers. Currently, for example on deserialization process, there are the "context" and "args" arguments, but I can't add arbitrary data as metadata about current model and document. An invoked serializer could have need to access, for example, to a document version metadata stored on the root of the document. The simpliest way to share this information, is to pass it with the call.