class Transformer(ABC):
    """Base class to type check all the transformer types in digneapy.
    A Transformer is any callable type that receives a sequence and transforms it
    to other sequence.
    """

    def __init__(self, name: str):
        self._name = name

    @abstractmethod
    def __call__(self, x: np.ndarray | list[IndType]) -> np.ndarray: ...

    def train(self, x: np.ndarray | list[IndType]):
        raise NotImplementedError("train method not implemented in Transformer")

    def predict(self, x: np.ndarray | list[IndType]) -> np.ndarray:
        return self.__call__(x)

    def save(self):
        raise NotImplementedError("save method not implemented in Transformer")