Symmetric Tree

7class Solution:
●    def isSymmetric(self, root) -> bool:
9        if not root:
......
12 
13    def isMirror(self, left, right) -> bool:
14        # Both null - symmetric at this position
15        if not left and not right:
16            return True
17        # One null, other not - asymmetric
......
20        # Values must match
21        if left.val != right.val:
22            return False
23        # Check outer pair and inner pair
24        outer = self.isMirror(left.left, right.right)
25        if not outer:
26            return False
27        inner = self.isMirror(left.right, right.left)
28        return outer and inner