input: Write a python function to simulate a game loop with running, looking, and fighting actions.
  assert type(game_loop()) == None
output: def game_loop():
      actions = ["running", "looking", "fighting"]
      for action in actions:
          if action == "running":
              print("You are running.")
          elif action == "looking":
              print("You are looking around.")
          elif action == "fighting":
              print("You are fighting.")
      return None