Find k Smallest Pair Sums

Given two integer arrays `nums1` and `nums2`, both sorted in non-decreasing order, and an integer `k`, return the `k` pairs with the smallest sums, where each pair contains one element from `nums1` and one element from `nums2`. If there are fewer than `k` possible pairs, return all of them. The output should be ordered by increasing pair sum; if multiple pairs have the same sum, any order among those ties is acceptable. You should implement a solution more efficient than generating every possible pair. In the interview, you are also expected to write a few tests and run the code. Example: - `nums1 = [1, 7, 11]` - `nums2 = [2, 4, 6]` - `k = 3` - Output: `[[1, 2], [1, 4], [1, 6]]`