from typing import Dict, List, Optional, Set, Tuple

class _Backend:
    def __init__(self, **settings) -> None:
        raise NotImplementedError()

    def lock(self, keys : List[List[str]], owner_key : Optional[str] = None) -> Tuple[bool, str]:
        raise NotImplementedError()

    def unlock(self, keys : List[List[str]], owner_key : str) -> bool:
        raise NotImplementedError()

    def keys(self) -> list:
        raise NotImplementedError()

    def exists(self, key : List[str]) -> bool:
        raise NotImplementedError()

    def delete(self, key : List[str]) -> bool:
        raise NotImplementedError()

    def dict_get(self, key : List[str], fields : List[str] = []) -> Dict[str, str]:
        raise NotImplementedError()

    def dict_update(self, key : List[str], fields : Dict[str, str] = {}) -> None:
        raise NotImplementedError()

    def dict_delete(self, key : List[str], fields : List[str] = []) -> None:
        raise NotImplementedError()

    def list_get_all(self, key : List[str]) -> List[str]:
        raise NotImplementedError()

    def list_push_last(self, key : List[str], item : str) -> None:
        raise NotImplementedError()

    def list_remove_first_occurrence(self, key : List[str], item: str) -> None:
        raise NotImplementedError()

    def set_add(self, key : List[str], item : str) -> None:
        raise NotImplementedError()

    def set_has(self, key : List[str], item : str) -> bool:
        raise NotImplementedError()

    def set_get_all(self, key : List[str]) -> Set[str]:
        raise NotImplementedError()

    def set_remove(self, key : List[str], item : str) -> None:
        raise NotImplementedError()

    def dump(self) -> List[Tuple[str, str, str]]:
        raise NotImplementedError()