input: Write a function to delete all duplicates in a given list of numbers. If the given list is empty then return an empty list.
  assert deleteDuplicates([1, 2, 2, 3, 4, 4, 5])==[1, 2, 3, 4, 5]
  assert deleteDuplicates([10, 20, 30, 20, 40, 30])==[10, 20, 30, 40]
  assert deleteDuplicates([5, 5, 5, 5, 5])==[5]
  assert deleteDuplicates([1, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0])==[1, 9, 8, 7, 6, 5, 4, 3, 2, 0]
  assert deleteDuplicates([])==[]
output: def deleteDuplicates(nums):
      return list(dict.fromkeys(nums))