docs: def mapper(self, meta_data, instance):
          """
          Pull out the meta data plate value and put it into the instance value
          :param meta_data: the original meta data
          :param instance: the original instance
          :return: the modified instance
          """
          d = dict(meta_data)
          v = d.pop(self.aggregation_meta_data)
          instance = deepcopy(instance)
          instance.value[self.aggregation_meta_data] = v
          return instance