input: Write a function to print the unique elements of a given list. The function should iterate through the list and print each element only once, even if it appears multiple times in the list. If the list is empty, the function should do nothing.
  def print_unique(my_list):
      seen = set()
      for x in my_list:
          if x not in seen:
              print(x)
              seen.add(x)
  
  assert print_unique([1, 2, 2, 3, 3, 4])==None
  assert print_unique([5, 5, 5, 5])==None
  assert print_unique([1, 2, 3, 4])==None
  assert print_unique([])==None
output: def print_unique(my_list):
      seen = set()
      for x in my_list:
          if x not in seen:
              print(x)
              seen.add(x)