[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/binary_tree/red_black_tree.py

@@ -651,7 +651,8 @@ def postorder_traverse(self) -> Iterator[int | None]:
 
     def __repr__(self) -> str:
         """Return a string representation of the tree."""
-        from pprint import pformat 
+        from pprint import pformat
+
         if self.left is None and self.right is None:
             return f"'{self.label} {(self.color and 'red') or 'blk'}'"
         return pformat(