[pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Author: pre-commit-ci[bot]

data_structures/lru_cache.py

@@ -2,21 +2,26 @@
 An implementation of a Least Recently Used (LRU) Cache.
 ... (the rest of the docstring is the same)
 """
+
 from __future__ import annotations
 from typing import Optional
 
+
 class Node:
     """A node in the doubly linked list."""
+
     def __init__(self, key: int, val: int) -> None:
         self.key, self.val = key, val
         self.prev: Optional[Node] = None
         self.next: Optional[Node] = None
 
+
 class LRUCache:
     """
     A Least Recently Used (LRU) Cache data structure.
     ... (the doctests are the same)
     """
+
     def __init__(self, capacity: int) -> None:
         if capacity <= 0:
             raise ValueError("Capacity must be a positive integer.")
@@ -67,6 +72,8 @@ def put(self, key: int, value: int) -> None:
                 self._remove(lru)
                 del self.cache[lru.key]
 
+
 if __name__ == "__main__":
     import doctest
-    doctest.testmod()
+
+    doctest.testmod()