code: func NewProtoWrapper(db keyval.CoreBrokerWatcher, serializer ...keyval.Serializer) *ProtoWrapper {
  	if len(serializer) > 0 {
  		return &ProtoWrapper{db, serializer[0]}
  	}
  	return &ProtoWrapper{db, &keyval.SerializerProto{}}
  }
docs: // NewProtoWrapper initializes proto decorator.
  // The default serializer is used - SerializerProto.