Python 2.7 为什么返回外部函数会产生错误？

我目前正在自学Python，使用Zed Shaw的《艰难的Python》。我目前正在练习43，我收到macOS High Serria 10.12.6上Terminal.app上的Bash错误：

 File "ex43.py", line 109
    return 'death'
SyntaxError: 'return' outside function

这是我从书中输入的代码：

from sys import exit
from random import randint


class Scene(object):


    def enter(self):
        print "This had not been coded yet. Subclass and implement enter()"
        pass


class Engine(object):

    def __init__(self, scene_map):
            self.scene_map = scene_map

    def play(self):
        current_scene = self.scene_map.opening_scene()

        while True:
            print "\n------------"
            next_scene_name = current_scene_map.opening_scene()
            current_scene_map = self.scene_map.next_scene(next_scene_name)


 class Death(Scene):


    quips = [
 "You died.  You kinda suck at this.",
 "Your mom would be proud...if she were smarter.",
 "Such a luser.",
 "I have a small puppy that's better at this."
    ]

    def enter(self):
        print Death.quips[randint(0, len(self.quips) -1)]
        exit(1)


class CentralCorridor(Scene):


        def enter(self):
            print "The Gothons of Planet Percal #25 have invaded your ship and destroyed"
            print "your entire crew.  You are the last surviving member and your last"
            print "mission is to get the neutron destruct bomb from the Weapons Armory,"
            print "put it in the bridge, and blow the ship up after getting into an "
            print "escape pod."
            print "\n"
            print "You're running down the central corridor to the Weapons Armory when"
            print "a Gothon jumps out, red scaly skin, dark grimy teeth, and evil clown costume"
            print "flowing around his hate filled body.  He's blocking the door to the"
            print "Armory and about to pull a weapon to blast you."

            action = raw_input("> ")

             if action == "shoot":
                 print "Quick on the draw you yank out your blaster and fire it at the Gothon."
                 print "His clown costume is flowing and moving around his body, which throws"
                 print "off your aim. Your laser hits his costume but misses him entirely. This"
                 print "completely ruins his brand new costume his mother bought him, which"
                 print "makes him fly into a rage and blast you repeatedly in the face until"
                 print "you are dead.  Then he eats you."
                 return 'death'

             elif action == "dodge":
                     print "Like a world class boxer you dodge, weave, slip and slide right"
                    print "as the Gothon's blaster cranks a laser past your head."
                    print "In the middle of your artful dodge your foot slips and you"
                    print "bang your head on the metal wall and pass out."
                    print "You wake up shortly after only to die as the Gothon stomps on"
                    print "your head and eats you."
                    return 'death'

            elif action == "tell a joke":
                 print "Lucky for you they made you learn Gothon insults in the academy."
                print "You tell the one Gothon joke you know:"
                print "Lbhe zbgure vf fb sng, jura fur fvgf nebhaq gur ubhfr, fur fvgf nebhaq gur ubhfr."
                print "The Gothon stops, tries not to laugh, then busts out laughing and can't move."
                print "While he's laughing you run up and shoot him square in the head"
                print "putting him down, then jump through the Weapon Armory door."
                return laser_weapon_armory

            else:
                print "DOES NOT COMPUTE!"
                return 'central_corridor'


class EscapePod(Scene):


     print "You rush through the ship desperately trying to make it to"
     print "the escape pod before the whole ship explodes.  It seems like"
     print "hardly any Gothons are on the ship, so your run is clear of"
     print "interference.  You get to the chamber with the escape pods, and"
     print "now need to pick one to take.  Some of them could be damaged"
     print "but you don't have time to look.  There's 5 pods, which one"
     print "do you take?"
     good_pod = randint(1, 5)
     guess = raw_input("[pod #]> ")

     if int(guess) != good_pod:
         print "You jump into pod %s and hit the eject button." % guess
         print "The pod escapes out into the void of space, then"
         print "implodes as the hull ruptures, crushing your body"
         print "into jam jelly."
         return 'death'

     else:

         print "You jump into pod %s and hit the eject button." % guess
         print "The pod easily slides out into space heading to"
         print "the planet below.  As it flies to the planet, you look"
         print "back and see your ship implode then explode like a"
         print "bright star, taking out the Gothon ship at the same"
         print "time.  You won!"
         return 'finished'


class LaserWeaponArmory(Scene):


    def enter(self):
        print "You do a dive roll onto the Weapon Armory, crouch and scan the room"
        print "for more Gothons that might be hiding.  It's dead quiet, too quiet."
        print "You stand up and run to the far side of the room and find the"
        print "neutron bomb in its container.  There's a keypad lock on the box"
        print "and you need the code to get the bomb out.  If you get the code"
        print "wrong 10 times then the lock closes forever and you can't"
        print "get the bomb.  The code is 3 digits."
        code = "%d%d%d" % (randint(1, 9), randint(1, 9), randint(1, 9))
        guess = raw_input("[keypad]> ")
        guesses = 0

        while guess != code and guesses < 10:
            print "BZZZZEDDD!"
            guesses = raw_input("[keypad]> ")

            if guess == code:

                print "The container clicks open and the seal breaks, letting gas out."
                print "You grab the neutron bomb and run as fast as you can to the"
                print "bridge where you must place it in the right spot."
                return 'the_bridge'

            else:

              print "The lock buzzes one last time and then you hear a sickening"
              print "melting sound as the mechanism is fused together."
              print "You decide to sit there, and finally the Gothons blow up the"
              print "ship from their ship and you die."
              return 'death'


class TheBridge(Scene):


    def enter(self):
        print "You burst onto the Bridge with the neutron destruct bomb"
        print "under your arm and surprise 5 Gothons who are trying to"
        print "take control of the ship.  Each of them has an even uglier"
        print "clown costume than the last.  They haven't pulled their"
        print "weapons out yet, as they see the active bomb under your"
        print "arm and don't want to set it off."

        action = raw_input("> ")

        if action == "throw the bomb":
            print "In a panic you throw the bomb at the group of Gothons"
            print "and make a leap for the door.  Right as you drop it a"
            print "Gothon shoots you right in the back killing you."
            print "As you die you see another Gothon frantically try to disarm"
            print "the bomb. You die knowing they will probably blow up when"
            print "it goes off."
            return 'death'

        elif action == "slowly place the bomb":

            print "You point your blaster at the bomb under your arm"
            print "and the Gothons put their hands up and start to sweat."
            print "You inch backward to the door, open it, and then carefully"
            print "place the bomb on the floor, pointing your blaster at it."
            print "You then jump back through the door, punch the close button"
            print "and blast the lock so the Gothons can't get out."
            print "Now that the bomb is placed you run to the escape pod to"
            print "get off this tin can."
            return 'escape_pod'

        else:

            print "DOES NOT COMPUTE!"
            return "the_bridge"


class Map(object):


    scenes = {
    'central_corridor': CentralCorridor,
    'laser_weapon_armory': LaserWeaponArmory,
    'the_bridge': TheBridge,
    'escape_pod': EscapePod,
     'death': Death
    }

    def __init__(self, start_scene):
        self.start_scene = start_scene

    def next_scene(self, scene_name):
        return Map.scenes.get(scene_name)

    def opening_scene(self):
        return



a_map = Map('central_corridor')
a_game = Engine(a_map)
a_game.play()

从系统导入退出
从随机导入randint
类场景（对象）：
def输入（自我）：
print“这还没有编码。子类和实现enter（）”
通过
类引擎（对象）：
定义初始（自我，场景贴图）：
self.scene\u map=scene\u map
def播放（自我）：
当前场景=self.scene\u map.opening\u scene（）
尽管如此：
打印“\n------------”
下一个场景名称=当前场景地图。打开场景（）
当前场景映射=self.scene\u map.next\u场景（next\u场景名称）
集体死亡（现场）：
俏皮话=[
“你死了，你有点烂。”，
“你妈妈会很骄傲的…如果她更聪明的话。”，
“真是个笨蛋。”，
“我有一只小狗，它在这方面做得更好。”
]
def输入（自我）：
打印死亡俏皮话[randint（0，len（self.quips）-1]
出口（1）
班中央指挥（现场）：
def输入（自我）：
打印“珀卡尔25号行星的哥特人入侵并摧毁了你的飞船”
打印“你的全体船员。你是最后一个幸存的成员，也是最后一个”
打印“任务是从武器库获取中子毁灭炸弹，”
打印“把它放在桥上，在进入一个
打印“逃生舱”
打印“\n”
打印“你正沿着中央走廊跑到武器库时”
印刷“一个哥特人跳了出来，红色鳞片皮肤，深色肮脏的牙齿，邪恶的小丑服装”
打印“在他充满仇恨的身体周围流动，他挡住了通往
打印“军械库，准备用武器炸你”
动作=原始输入（“>”）
如果动作==“射击”：
打印“快速抽签，你拔出你的爆能枪，向Gothon开火。”
打印“他的小丑服装在他身上飘动，这使他
打印“偏离你的目标。你的激光击中了他的服装，但完全没有击中他。这个”
印刷“完全毁了他母亲给他买的全新服装，这”
打印“让他勃然大怒，不断地朝你脸上开枪，直到”
打印“你死了，然后他吃了你。”
返回“死亡”
elif动作==“闪避”：
打印“像一个世界级的拳击手，你躲闪，编织，滑动和滑动的权利”
打印“当Gothon的爆能枪转动激光经过你的头部时。”
打印“在你巧妙躲闪的过程中，你的脚滑倒了，你”
打印“把头撞在金属墙上，然后昏倒。”
打印“你醒来不久，却在哥特洪人跺脚时死去”
打印“你的头吃掉你。”
返回“死亡”
elif action==“讲个笑话”：
印刷“幸运的是，他们让你在学院里学会了Gothon侮辱。”
打印“你讲了一个你知道的哥顿笑话：”
打印“Lbhe zbgure vf fb sng，jura fur fvgf nebhaq gur ubhfr，fur fvgf nebhaq gur ubhfr。”
打印“Gothon停下来，试着不笑，然后大笑起来，动弹不得。”
打印“当他笑的时候，你跑过来朝他脑袋上一枪”
打印“放下他，然后跳进武器库的门。”
返回激光武器库
其他：
打印“不计算！”
返回“中央走廊”
类转义记事本（场景）：
打印“你在船上拼命冲向”
打印“整艘船爆炸前的逃生舱，看起来像”
打印“船上几乎没有哥特霍恩人，所以你的跑步没有障碍”
打印“干扰，你带着逃生舱进入房间，然后”
打印“现在需要挑选一个，其中一些可能会损坏”
打印“但是你没有时间看。有5个豆荚，哪一个？”
打印“你接受吗？”
好的pod=randint（1,5）
猜测=原始输入（“[pod#]>”）
如果int（猜测）！=好!
打印“您跳入%s舱并按下弹出按钮。”%guess
打印“吊舱逃逸到空间的空隙中，然后”
打印“船体破裂时内爆，压碎你的身体”
打印成果酱果冻
返回“死亡”
其他：
打印“您跳入%s舱并按下弹出按钮。”%guess
打印“吊舱很容易滑出到空间中，朝向”
打印“下面的星球。当它飞到星球上时，你看”
打印“返回并看到你的飞船内爆，然后像炸弹一样爆炸”
打印“明亮的星星，同时干掉Gothon飞船”
打印“时间，你赢了！”
返回“已完成”
类激光武器（场景）：
def输入（自我）：
打印“你俯冲到武器库，蹲下并扫描房间”
打印“寻找更多可能隐藏的哥特人。这里非常安静，太安静了。”
打印“你站起来，跑到房间的另一边，找到
打印“中子弹在它的容器里，盒子上有一个键盘锁”
打印“你需要密码才能把炸弹拿出来如果你得到密码”
打印“错误10次，然后锁永远关闭，而您不能”
打印“获取炸弹。代码为3位。”
code=“%d%d%d”%（randint（1,9），randint（1,9），randint（1,9））
猜测=原始输入（“[键盘]>”）
猜测=0
猜猜看！=编码和猜测<10：
打印“bzzeddd！”
猜测=原始输入（“[键盘]>”）
如果猜测=co
def enter(self):
    print "You rush through the ship desperately trying to make it to"
    print "the escape pod before the whole ship explodes.  It seems like"
    print "hardly any Gothons are on the ship, so your run is clear of"
    print "interference.  You get to the chamber with the escape pods, and"
    print "now need to pick one to take.  Some of them could be damaged"
    print "but you don't have time to look.  There's 5 pods, which one"
    print "do you take?"
    good_pod = randint(1, 5)
    guess = raw_input("[pod #]> ")
    if int(guess) != good_pod:
        print "You jump into pod %s and hit the eject button." % guess
        print "The pod escapes out into the void of space, then"
        print "implodes as the hull ruptures, crushing your body"
        print "into jam jelly."
        return 'death'
    else:
        print "You jump into pod %s and hit the eject button." % guess
        print "The pod easily slides out into space heading to"
        print "the planet below.  As it flies to the planet, you look"
        print "back and see your ship implode then explode like a"
        print "bright star, taking out the Gothon ship at the same"
        print "time.  You won!"
        return 'finished'