input: Write a function to find all the unique pairs of numbers that add up to the target sum.
  assert findPairs([2, 3, 5, 7], 10) == [(3, 7)]
  assert findPairs([1, 2, 3, 4, 5, 6], 7) == [(1, 6), (2, 5), (3, 4)]
  assert findPairs([0, -1, -2, 3, 1, 2], 1) == [(0, 1), (-1, 2)]
output: def findPairs(nums, target):
      pairs = []
      seen = set()
      for num in nums:
          complement = target - num
          if complement in seen:
              pairs.append((complement, num))
          seen.add(num)
      return pairs