#### Binary Tree Mirror

S
```"""
Problem Description:
Given a binary tree, return its mirror.
"""

def binary_tree_mirror_dict(binary_tree_mirror_dictionary: dict, root: int):
if not root or root not in binary_tree_mirror_dictionary:
return
left_child, right_child = binary_tree_mirror_dictionary[root][:2]
binary_tree_mirror_dictionary[root] = [right_child, left_child]
binary_tree_mirror_dict(binary_tree_mirror_dictionary, left_child)
binary_tree_mirror_dict(binary_tree_mirror_dictionary, right_child)

def binary_tree_mirror(binary_tree: dict, root: int = 1) -> dict:
"""
>>> binary_tree_mirror({ 1: [2,3], 2: [4,5], 3: [6,7], 7: [8,9]}, 1)
{1: [3, 2], 2: [5, 4], 3: [7, 6], 7: [9, 8]}
>>> binary_tree_mirror({ 1: [2,3], 2: [4,5], 3: [6,7], 4: [10,11]}, 1)
{1: [3, 2], 2: [5, 4], 3: [7, 6], 4: [11, 10]}
>>> binary_tree_mirror({ 1: [2,3], 2: [4,5], 3: [6,7], 4: [10,11]}, 5)
Traceback (most recent call last):
...
ValueError: root 5 is not present in the binary_tree
>>> binary_tree_mirror({}, 5)
Traceback (most recent call last):
...
ValueError: binary tree cannot be empty
"""
if not binary_tree:
raise ValueError("binary tree cannot be empty")
if root not in binary_tree:
raise ValueError(f"root {root} is not present in the binary_tree")
binary_tree_mirror_dictionary = dict(binary_tree)
binary_tree_mirror_dict(binary_tree_mirror_dictionary, root)
return binary_tree_mirror_dictionary

if __name__ == "__main__":
binary_tree = {1: [2, 3], 2: [4, 5], 3: [6, 7], 7: [8, 9]}
print(f"Binary tree: {binary_tree}")
binary_tree_mirror_dictionary = binary_tree_mirror(binary_tree, 5)
print(f"Binary tree mirror: {binary_tree_mirror_dictionary}")
```