code: def write(self, proto):
      
      super(PreviousValueModel, self).writeBaseToProto(proto.modelBase)
  
      proto.fieldNames = self._fieldNames
      proto.fieldTypes = self._fieldTypes
      if self._predictedField:
        proto.predictedField = self._predictedField
      proto.predictionSteps = self._predictionSteps
docs: Serialize via capnp
  
      :param proto: capnp PreviousValueModelProto message builder