input: Write a function to find combinations of pairs that sum up to a given total.
  assert findCombinations([1, 2, 3, 4, 5], 7) == [[3, 4], [2, 5]]
  assert findCombinations([10, 20, 30, 40, 50], 50) == [[10, 40]]
  assert findCombinations([1, 1, 1, 2, 2], 3) == [[1, 2], [1, 2]]
output: def findCombinations(nums, target):
      result = []
      seen = set()
      
      for num in nums:
          complement = target - num
          if complement in seen:
              result.append([complement, num])
          seen.add(num)
      
      return result