input: 
  def deleteDuplicates(numbers: list) -> list:
      """ Deletes all duplicates in a given list of numbers and returns the list without duplicates.
      >>> deleteDuplicates([1, 2, 3, 4, 1, 2, 5])
      [1, 2, 3, 4, 5]
      >>> deleteDuplicates([10, 10, 20, 30, 40, 40, 50])
      [10, 20, 30, 40, 50]
      >>> deleteDuplicates([])
      []
      """
  
output:     seen = set()
      result = []
      for num in numbers:
          if num not in seen:
              seen.add(num)
              result.append(num)
      return result