input: Write a function to find pairs of numbers that sum up to a target number.
  assert sumPairs([3, 5, 7, 8, 12], 11) == [[3, 8]]
  assert sumPairs([1, 2, 3, 4, 5], 6) == [[1, 5], [2, 4]]
  assert sumPairs([0, -1, 1, -2, 2, 3], 1) == [[0, 1], [-1, 2], [-2, 3]]
  assert sumPairs([], 5) == []
  assert sumPairs([2, 4, 6, 8], 10) == [[2, 8], [4, 6]]
output: def sumPairs(numbers, target):
      pairs = []
      seen = set()
      for number in numbers:
          complement = target - number
          if complement in seen:
              pairs.append([complement, number])
          seen.add(number)
      return pairs