Given a palindromic string palindrome, replace exactly one character by any lowercase English letter so that the string becomes the lexicographically smallest possible string that isn't a palindrome.
After doing so, return the final string.  If there is no way to do so, return the empty string.
Example 1:
Input: palindrome = "abccba"
Output: "aaccba"
Example 2:
Input: palindrome = "a"
Output: ""
Constraints:
1 <= palindrome.length <= 1000
palindrome consists of only lowercase English letters.
class Solution:
    def breakPalindrome(self, palindrome: str) -> str:
        if len(palindrome) == 1:
            return ''
        for i, val in enumerate(palindrome):
            if val != 'a' and i != len(palindrome) // 2:
                return palindrome[:i] + 'a' + palindrome[i+1:]
            elif val == 'a' and i == len(palindrome) - 1:
                return palindrome[:-1] + 'b'

class Solution:
    def breakPalindrome(self, palindrome: str) -> str:
        if len(palindrome) == 1:
            return ''
        for i, val in enumerate(palindrome):
            if val != 'a' and i != len(palindrome) // 2:
                return palindrome[:i] + 'a' + palindrome[i+1:]
            elif val == 'a' and i == len(palindrome) - 1:
                return palindrome[:-1] + 'b'
