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

Given a string s, return the number of different non-empty palindromic subsequences in s. Since the answer may be very large, return it modulo 109 + 7.
A subsequence of a string is obtained by deleting zero or more characters from the string.
A sequence is palindromic if it is equal to the sequence reversed.
Two sequences a1, a2, ... and b1, b2, ... are different if there is some i for which ai != bi.
 
Please complete the following python code precisely:
```python
class Solution:
    def countPalindromicSubsequences(self, s: str) -> int:
```