input: Write a function to remove duplicate elements from a list.
  assert removeDuplicates([1, 2, 2, 3, 4, 4, 5]) == [1, 2, 3, 4, 5]
  assert removeDuplicates([5, 5, 5, 5, 5]) == [5]
  assert removeDuplicates([3, 8, 4, 3, 2, 8]) == [3, 8, 4, 2]
  assert removeDuplicates([]) == []
output: def removeDuplicates(lst):
      seen = set()
      result = []
      for item in lst:
          if item not in seen:
              seen.add(item)
              result.append(item)
      return result