input: Write a function to remove duplicates from a list and return a new list with unique elements in the original order.
  def remove_duplicates(my_list):
   return list(dict.fromkeys(my_list))
  
  my_list = [1, 2, 3, 4, 3, 2, 1]
  
  assert remove_duplicates(my_list) == [1, 2, 3, 4]
  assert remove_duplicates([1, 1, 1, 1]) == [1]
  assert remove_duplicates([]) == []
  assert remove_duplicates([5, 6, 7, 7, 6, 5]) == [5, 6, 7]
output: def remove_duplicates(my_list):
      return list(dict.fromkeys(my_list))