input: Write a function to find duplicate elements in a list.
  assert findDuplicates([1, 2, 3, 4, 5, 2, 3, 1, 6, 3]) == [2, 3, 1, 3]
  assert findDuplicates([1, 1, 2, 3, 4, 4, 5, 6, 6]) == [1, 4, 6]
  assert findDuplicates([10, 20, 30, 40, 50]) == []
  assert findDuplicates([5, 5, 5, 5, 5]) == [5, 5, 5, 5]
output: def findDuplicates(lst):
      seen = set()
      duplicates = []
      for item in lst:
          if item in seen:
              duplicates.append(item)
          else:
              seen.add(item)
      return duplicates