input: Write a function to delete all duplicates in a given list of numbers. The function should return a new list with all unique elements in the order they first appeared in the original list.
  assert deleteDuplicates([1, 2, 3, 1, 2, 3, 4, 5])==[1, 2, 3, 4, 5]
  assert deleteDuplicates([1, 1, 1, 1, 1])==[1]
  assert deleteDuplicates([1, 2, 3, 4, 5])==[1, 2, 3, 4, 5]
  assert deleteDuplicates([])==[]
  assert deleteDuplicates([10, 20, 30, 10, 20, 30, 40, 50])==[10, 20, 30, 40, 50]
output: def deleteDuplicates(nums):
      seen = set()
      result = []
      for num in nums:
          if num not in seen:
              seen.add(num)
              result.append(num)
      return result