input: Write a function to print the unique elements of a given list.
  
  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, 4, 4, 5])
  assert print_unique([1, 1, 1, 1, 1])
  assert print_unique([])
  assert print_unique([5, 5, 6, 6, 7, 7, 7])
  assert print_unique([8, 9, 10, 11, 12, 12])
  
  # The output of the assert statements should be the unique elements printed to the console.
output: def print_unique(my_list):
      seen = set()
      for x in my_list:
          if x not in seen:
              print(x)
              seen.add(x)