code: func EncodeList(e Encoder, objects []Object) error {
  	var errs []error
  	for i := range objects {
  		data, err := Encode(e, objects[i])
  		if err != nil {
  			errs = append(errs, err)
  			continue
  		}
  		// TODO: Set ContentEncoding and ContentType.
  		objects[i] = &Unknown{Raw: data}
  	}
  	return errors.NewAggregate(errs)
  }
docs: // EncodeList ensures that each object in an array is converted to a Unknown{} in serialized form.
  // TODO: accept a content type.