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

You are given a 0-indexed string s that has lowercase English letters in its even indices and digits in its odd indices.
You must perform an operation shift(c, x), where c is a character and x is a digit, that returns the xth character after c.

For example, shift('a', 5) = 'f' and shift('x', 0) = 'x'.

For every odd index i, you want to replace the digit s[i] with the result of the shift(s[i-1], s[i]) operation.
Return s after replacing all digits. It is guaranteed that shift(s[i-1], s[i]) will never exceed 'z'.
Note that shift(c, x) is not a preloaded function, but an operation to be implemented as part of the solution.
 
Please complete the following python code precisely:
```python
class Solution:
    def replaceDigits(self, s: str) -> str:
```