Closes #219

src/libbot/cache/classes/cache.py

@@ -1,5 +1,5 @@
 from abc import ABC, abstractmethod
-from typing import Any, Dict
+from typing import Any, Dict, Optional
 
 import pymemcache
 import redis
@@ -27,16 +27,16 @@ class Cache(ABC):
         pass
 
     @abstractmethod
-    def set_json(self, key: str, value: Any) -> None:
+    def set_json(self, key: str, value: Any, ttl_seconds: Optional[int] = None) -> None:
         # TODO This method must also carry out ObjectId conversion!
         pass
 
     @abstractmethod
-    def set_string(self, key: str, value: str) -> None:
+    def set_string(self, key: str, value: str, ttl_seconds: Optional[int] = None) -> None:
         pass
 
     @abstractmethod
-    def set_object(self, key: str, value: Any) -> None:
+    def set_object(self, key: str, value: Any, ttl_seconds: Optional[int] = None) -> None:
         pass
 
     @abstractmethod