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

Given an m x n matrix, return true if the matrix is Toeplitz. Otherwise, return false.
A matrix is Toeplitz if every diagonal from top-left to bottom-right has the same elements.
 
Please complete the following python code precisely:
```python
class Solution:
    def isToeplitzMatrix(self, matrix: List[List[int]]) -> bool:
```