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

You are given a string num consisting of digits only.
Return the largest palindromic integer (in the form of a string) that can be formed using digits taken from num. It should not contain leading zeroes.
Notes:

You do not need to use all the digits of num, but you must use at least one digit.
The digits can be reordered.

 
Please complete the following python code precisely:
```python
class Solution:
    def largestPalindromic(self, num: str) -> str:
```