code: def new(cls, **kwargs):
          
          kwargs = cls.preprocess_kwargs_before_new(kwargs)
          if cls.__mapper__.polymorphic_on is not None:
              discriminator_key = cls.__mapper__.polymorphic_on.name
              discriminator_val = kwargs.get(discriminator_key)
              if discriminator_val is not None and discriminator_val in cls.__mapper__.polymorphic_map:
                  actual_cls = cls.__mapper__.polymorphic_map[discriminator_val].class_
                  return actual_cls(
                      **subdict(
                          actual_cls._preprocess_params(kwargs),
                          actual_cls.all_settable_keys())
                  )
          return cls(**subdict(cls._preprocess_params(kwargs), cls.all_settable_keys()))
docs: Returns a new, unsaved instance of the model class.