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

Given a list of non-negative integers nums, arrange them such that they form the largest number and return it.
Since the result may be very large, so you need to return a string instead of an integer.
 
Please complete the following python code precisely:
```python
class Solution:
    def largestNumber(self, nums: List[int]) -> str:
```