feat: add more type hints

fastapi_cache/backends/redis.py

@@ -1,4 +1,4 @@
-from typing import Tuple
+from typing import Tuple, Optional
 
 from redis.asyncio.client import Redis
 
@@ -13,15 +13,16 @@ class RedisBackend(Backend):
         async with self.redis.pipeline(transaction=True) as pipe:
             return await (pipe.ttl(key).get(key).execute())
 
-    async def get(self, key) -> str:
+    async def get(self, key: str) -> Optional[str]:
         return await self.redis.get(key)
 
-    async def set(self, key: str, value: str, expire: int = None):
+    async def set(self, key: str, value: str, expire: Optional[int] = None) -> None:
         return await self.redis.set(key, value, ex=expire)
 
-    async def clear(self, namespace: str = None, key: str = None) -> int:
+    async def clear(self, namespace: Optional[str] = None, key: Optional[str] = None) -> int:
         if namespace:
             lua = f"for i, name in ipairs(redis.call('KEYS', '{namespace}:*')) do redis.call('DEL', name); end"
             return await self.redis.eval(lua, numkeys=0)
         elif key:
             return await self.redis.delete(key)
+        return 0