Please solve the programming task below using a self-contained code snippet in a markdown code block.

You are given two strings s and t.
String t is generated by random shuffling string s and then add one more letter at a random position.
Return the letter that was added to t.
 
Please complete the following python code precisely:
```python
class Solution:
    def findTheDifference(self, s: str, t: str) -> str:
```