import time
from typing import Generic, TypeVar

K = TypeVar("K")
V = TypeVar("V")

class TTLCache(Generic[K, V]):
    def __init__(self, ttl_seconds: int = 3600) -> None:
        self.ttl: int = ttl_seconds
        self.__cache: dict[K, tuple[V, float]] = {}

    def get(self, key: K) -> V | None:
        if key in self.__cache:
            value, timestamp = self.__cache[key]
            if time.time() - timestamp < self.ttl:
                return value
            else:
                del self.__cache[key]
        return None

    def set(self, key: K, value: V) -> None:
            self.__cache[key] = (value, time.time())

    def clear(self) -> None:
        self.__cache.clear()