class ExtendedDict(dict):
    def __setattr__(self, key, value):
        if type(key) is str:
            self.__dict__[key] = value
        else:
            raise ValueError

    def __setitem__(self, key, value):
        if type(key) is str:
            self.__dict__[key] = value
        else:
            raise ValueError

    def __getattr__(self, key):
        if key in self.__dict__:
            return self.__dict__.get(key)
        else:
            raise ValueError

    def __getitem__(self, key):
        if isinstance(key, slice):
            list_sort = sorted(self.__dict__.items(), key=lambda val: val[0])
            return list_sort[key.start:key.stop:key.step]
        elif key in self.__dict__:
            return self.__dict__.get(key)
        else:
            raise ValueError

    def __delattr__(self, key):
        if key in self.__dict__:
            del self.__dict__[key]
        else:
            raise ValueError

    def __delitem__(self, key):
        if key in self.__dict__:
            del self.__dict__[key]
        else:
            raise ValueError