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

Given two strings s and t, return the number of distinct subsequences of s which equals t.
The test cases are generated so that the answer fits on a 32-bit signed integer.
 
Please complete the following python code precisely:
```python
class Solution:
    def numDistinct(self, s: str, t: str) -> int:
```