input: Write a function to remove duplicates from a list and return the list in the same order. If the input list is empty, return an empty list.
  
  def remove_duplicates(my_list):
      return list(dict.fromkeys(my_list))
  
  assert remove_duplicates([1, 2, 3, 4, 3, 2, 1])==[1, 2, 3, 4]
  assert remove_duplicates([5, 5, 5, 5, 5])==[5]
  assert remove_duplicates([])==[]
  assert remove_duplicates([9, 8, 7, 6, 5, 4, 9, 8, 7, 6, 5])==[9, 8, 7, 6, 5, 4]
  assert remove_duplicates([1])==[1]
output: def remove_duplicates(my_list):
      seen = set()
      result = []
      for item in my_list:
          if item not in seen:
              seen.add(item)
              result.append(item)
      return result