class BaseMemory:
    def __init__(self) -> None:
        raise NotImplementedError
    
    def append(self, message: str) -> None:
        raise NotImplementedError
    
    def pop(self) -> None:
        raise NotImplementedError
    
    def clear(self) -> None:
        raise NotImplementedError
    
    def load(self) -> None:
        raise NotImplementedError
    
    def save(self) -> None:
        raise NotImplementedError