input: Write a function to remove duplicates from a given list. Return the list containing only the unique elements in the same order they first appeared.
  
  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([10, 20, 30, 20, 10, 5]) == [10, 20, 30, 5]
output: def remove_duplicates(my_list):
      return list(dict.fromkeys(my_list))