docs: def _add_dynamic_field_to_model(cls, field, field_name):
          """
          Add a copy of the DynamicField "field" to the current class and its
          subclasses using the "field_name" name
          """
          # create the new field
          new_field = field._create_dynamic_version()
          new_field.name = field_name
          new_field._attach_to_model(cls)
  
          # set it as an attribute on the class, to be reachable
          setattr(cls, "_redis_attr_%s" % field_name, new_field)
  
          # NOTE: don't add the field to the "_fields" list, to avoid use extra
          #       memory to each future instance that will create a field for each
          #       dynamic one created
  
          # # add the field to the list to avoid to done all of this again
          # # (_fields is already on this class only, not subclasses)
          # cls._fields.append(field_name)
  
          # each subclass needs its own copy
          for subclass in cls.__subclasses__():
              subclass._add_dynamic_field_to_model(field, field_name)
  
          return new_field