diff --git a/data_structures/binary_tree/binary_search_tree.py b/data_structures/binary_tree/binary_search_tree.py
index cd88cc10e697..c72195424c7c 100644
--- a/data_structures/binary_tree/binary_search_tree.py
+++ b/data_structures/binary_tree/binary_search_tree.py
@@ -40,7 +40,7 @@ def __reassign_nodes(self, node: Node, new_children: Node | None) -> None:
             else:
                 node.parent.left = new_children
         else:
-            self.root = None
+            self.root = new_children
 
     def is_right(self, node: Node) -> bool:
         if node.parent and node.parent.right:
diff --git a/maths/euclidean_distance.py b/maths/euclidean_distance.py
index 22012e92c9cf..95a59c762329 100644
--- a/maths/euclidean_distance.py
+++ b/maths/euclidean_distance.py
@@ -1,12 +1,11 @@
 from __future__ import annotations
 
 from collections.abc import Iterable
-from typing import Union
 
 import numpy as np
 
-Vector = Union[Iterable[float], Iterable[int], np.ndarray]
-VectorOut = Union[np.float64, int, float]
+Vector = Iterable[float] | Iterable[int] | np.ndarray
+VectorOut = np.float64 | int | float
 
 
 def euclidean_distance(vector_1: Vector, vector_2: Vector) -> VectorOut: