class ExtendedDict(dict):
    def __setitem__(self, key, value):
        if isinstance(key, str):
            super().__setitem__(key, value)
        else:
            raise ValueError

    def __setattr__(self, key, value):
        if isinstance(key, str):
            self[key] = value
        else:
            raise ValueError

    def __getitem__(self, key):
        if isinstance(key, slice):
            list_sort = sorted(self.items(), key=lambda val: val[0])
            return list_sort[key.start:key.stop:key.step]
        elif key in self:
            return super().__getitem__(key)
        elif not isinstance(key, str):
            raise ValueError
        else:
            raise KeyError

    def __getattr__(self, key):
        if key in self:
            return self.get(key)
        elif not isinstance(key, str):
            raise ValueError
        else:
            raise KeyError

    def __delitem__(self, key):
        if key in self:
            super().__delitem__(key)
        elif not isinstance(key, str):
            raise ValueError
        else:
            raise KeyError

    def __delattr__(self, key):
        if key in self:
            del self[key]
        elif not isinstance(key, str):
            raise ValueError
        else:
            raise KeyError