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

We are given a list nums of integers representing a list compressed with run-length encoding.
Consider each adjacent pair of elements [freq, val] = [nums[2*i], nums[2*i+1]] (with i >= 0).  For each such pair, there are freq elements with value val concatenated in a sublist. Concatenate all the sublists from left to right to generate the decompressed list.
Return the decompressed list.
 
Please complete the following python code precisely:
```python
class Solution:
    def decompressRLElist(self, nums: List[int]) -> List[int]:
```