input: Write a python function to find pairs in a list that sum to 10.
  assert findPairs([1, 2, 3, 4, 5, 6]) == [(4, 6)]
  assert findPairs([1, 2, 8, 9, 10, 5, 5]) == [(1, 9), (2, 8), (5, 5)]
  assert findPairs([2, 4, 6, 3, 7, 1, 9]) == [(1, 9), (3, 7)]
output: def findPairs(lst):
      pairs = []
      seen = set()
      for number in lst:
          complement = 10 - number
          if complement in seen:
              pairs.append((complement, number))
          seen.add(number)
      return pairs