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

Given an array of n integers nums and an integer target, find the number of index triplets i, j, k with 0 <= i < j < k < n that satisfy the condition nums[i] + nums[j] + nums[k] < target.
 
Please complete the following python code precisely:
```python
class Solution:
    def threeSumSmaller(self, nums: List[int], target: int) -> int:
```