input: 
  def delete_duplicates(numbers: List[int]) -> List[int]:
      """ Remove all duplicates from a given list of numbers, returning a list of unique elements in the same order as they appear.
      >>> delete_duplicates([3, 1, 2, 3, 4])
      [3, 1, 2, 4]
      >>> delete_duplicates([5, 2, 7, 2, 5, 8, 7, 9])
      [5, 2, 7, 8, 9]
      """
  
output:     seen = set()
      result = []
      for num in numbers:
          if num not in seen:
              seen.add(num)
              result.append(num)
      return result