docs: def _inventory(self):
          """
          Return (and create if needed) the internal inventory field, a SetField
          used to track all dynamic versions used on a specific instance.
          """
          if self.dynamic_version_of:
              return self.dynamic_version_of._inventory
  
          if not hasattr(self, '_inventory_field'):
              self._inventory_field = limpyd_fields.SetField()
              self._inventory_field._attach_to_model(self._model)
              self._inventory_field._attach_to_instance(self._instance)
              self._inventory_field.lockable = True
              self._inventory.name = self.name
  
          return self._inventory_field