input: def print_unique(my_list):
      seen = set()
      for x in my_list:
          if x not in seen:
              print(x)
              seen.add(x)
  
  
  # Example usage:
  # >>> print_unique([1, 2, 2, 3, 4, 4, 5])
  # 1
  # 2
  # 3
  # 4
  # 5
output:     seen = set()
      for x in my_list:
          if x not in seen:
              print(x)
              seen.add(x)