input: 
  def remove_duplicates(integers: List[int]) -> List[int]:
      """ Remove all duplicate elements from a given list of integers and return the resulting list.
      >>> remove_duplicates([1, 2, 3, 2, 4, 5, 6, 3])
      [1, 2, 3, 4, 5, 6]
      >>> remove_duplicates([5, 5, 5, 5])
      [5]
      """
  
output:     seen = set()
      result = []
      for num in integers:
          if num not in seen:
              seen.add(num)
              result.append(num)
      return result