diff --git a/mypy.ini b/mypy.ini
index 7dbc7c4ffc80..de473bbb2bc6 100644
--- a/mypy.ini
+++ b/mypy.ini
@@ -2,4 +2,3 @@
 ignore_missing_imports = True
 install_types = True
 non_interactive = True
-exclude = (other/least_recently_used.py)
diff --git a/other/least_recently_used.py b/other/least_recently_used.py
index 9d6b6d7cb6a6..302a06c1fd3b 100644
--- a/other/least_recently_used.py
+++ b/other/least_recently_used.py
@@ -1,10 +1,13 @@
 import sys
+from abc import ABCMeta
 from collections import deque
 
 
 class LRUCache:
     """Page Replacement Algorithm, Least Recently Used (LRU) Caching."""
 
+    __metaclass__ = ABCMeta
+
     dq_store = object()  # Cache store of keys
     key_reference_map = object()  # References of the keys in cache
     _MAX_CAPACITY: int = 10  # Maximum capacity of cache