Add pyupgrade to pre-commit

Author: cclauss

.pre-commit-config.yaml

@@ -22,6 +22,12 @@ repos:
       - id: isort
         args:
           - --profile=black
+  - repo: https://github.com/asottile/pyupgrade
+    rev: v2.29.0
+    hooks:
+      - id: pyupgrade
+        args:
+          - --py39-plus
   - repo: https://gitlab.com/pycqa/flake8
     rev: 3.9.1
     hooks:

data_structures/binary_tree/merge_two_binary_trees.py

@@ -21,7 +21,7 @@ def __init__(self, value: int = 0) -> None:
         self.right: Node | None = None
 
 
-def merge_two_binary_trees(tree1: Node | None, tree2: Node | None) -> Optional[Node]:
+def merge_two_binary_trees(tree1: Node | None, tree2: Node | None) -> Node | None:
     """
     Returns root node of the merged tree.
 

data_structures/linked_list/skip_list.py

@@ -12,7 +12,7 @@
 
 
 class Node(Generic[KT, VT]):
-    def __init__(self, key: Union[KT, str] = "root", value: Optional[VT] = None):
+    def __init__(self, key: KT | str = "root", value: VT | None = None):
         self.key = key
         self.value = value
         self.forward: list[Node[KT, VT]] = []