code: def _serialize_model_helper(self, model, field_dict=None):
          
          field_dict = field_dict or self.dot_field_list_to_dict()
          if model is None:
              return None
  
          if isinstance(model, Query):
              model = model.all()
  
          if isinstance(model, (list, set)):
              return [self.serialize_model(m, field_dict=field_dict) for m in model]
  
          model_dict = {}
          for name, sub in six.iteritems(field_dict):
              value = getattr(model, name)
              if sub:
                  value = self.serialize_model(value, field_dict=sub)
              model_dict[name] = value
          return model_dict
docs: A recursive function for serializing a model
          into a json ready format.