input: Write a function to remove duplicates from a list. The function should take a list as input and return a new list with all duplicates removed, while preserving the order of the original elements. If the 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]
  assert remove_duplicates([10, 20, 30, 20, 10])==[10, 20, 30]
  assert remove_duplicates([])==[]
output: def remove_duplicates(my_list):
      return list(dict.fromkeys(my_list))