code: def safe_data(self):
          
          if self.data is None:
              raise DeadEntityException(
                  "Entity {}:{} is dead - its attributes can no longer be "
                  "accessed. Use the .previous() method on this object to get "
                  "a copy of the object at its previous state.".format(
                      self.entity_type, self.entity_id))
          return self.data
docs: The data dictionary for this entity.
  
          If this `ModelEntity` points to the dead state, it will
          raise `DeadEntityException`.