code: def _delete_dynamic_versions(self):
          
          if self.dynamic_version_of:
              raise ImplementationError(u'"_delete_dynamic_versions" can only be '
                                        u'executed on the base field')
          inventory = self._inventory
          for dynamic_part in inventory.smembers():
              name = self.get_name_for(dynamic_part)
              # create the field
              new_field = self._create_dynamic_version()
              new_field.name = name
              new_field._dynamic_part = dynamic_part  # avoid useless computation
              new_field._attach_to_model(self._model)
              new_field._attach_to_instance(self._instance)
              # and delete its content
              new_field.delete()
  
          inventory.delete()
docs: Call the `delete` method of all dynamic versions of the current field
          found in the inventory then clean the inventory.