Ex43 AttributeError: 'NoneType' object has no attribute 'enter'

I am having the same problem as someone in a previous post. I saw a suggestion to start a new thread to get more eyeballs on it.

I check and all my enter() present a return or include a pass. I cannot get past inputing Adventure and going to the Adventure class. I get this error:

File “motato.py”, line 138, in
a_game.play()
File “motato.py”, line 24, in play
next_scene_name = current_scene.enter()
AttributeError: ‘NoneType’ object has no attribute ‘enter’

from sys import exit
from sys import argv
from random import randint
from textwrap import dedent
from os.path import exists
from datetime import datetime, timedelta, date
import time

script, from_file, to_file = argv

class Timer():
    def timer(self):
        pass

class Engine():
    def __init__(self, universe_portal):
        self.universe_portal = universe_portal

    def play(self):
        current_scene = self.universe_portal.opening_scene()
        last_scene = self.universe_portal.next_scene('finished')

        while current_scene != last_scene:
            next_scene_name = current_scene.enter()
            current_scene = self.universe_portal.next_scene(next_scene_name)
        current_scene.enter()

class Scene():
    def enter(self):
        print("SCENE DUMMY")
        exit(1)

class Death(Scene):
    def enter(self):
        pass

class Portal(Scene):

    def enter(self):
        print(dedent("""You are safe at home. What do you want to do?
    [ Check Inventory ] [ Adventure ] [ Brew ]
        """))

        choice = input("> ")

        if 'inventory' or 'Inventory' in choice:
            return 'inventory'

        elif 'adventure' or 'Adventure' in choice:
            return 'adventure'

        elif 'brew' in choice:
            return 'brew_system'

        else:
            print("DOES NOT COMPUTE")
            return 'portal'

class Adventure(Scene):

    def enter(self):
        print(dedent(""""
        Where shall we start our adventure?
        [ Rivers of Plenty ] [ SUGAR HELL ] [ Ginger Forest ]
        """))

        space_travel = input("> ")

        if 'rivers' or 'Rivers' in space_travel:
            return 'rivers_of_plenty'

        elif 'hell' or 'Hell' in space_travel:
            return 'sugar_hell'

        elif 'ginger' or 'Ginger' in space_travel:
            return 'ginger_forest'

        else:
            print("CANNOT COMPUTE")
            return 'portal'


class Inventory(Scene):
    def enter(self):
        pass

class RiversOfPlenty(Scene):
    def enter(self):
        pass
    def WaterGoddess(self):
        pass

class SugarHell(Scene):
    def enter(self):
        pass
    def SweetSatan(self):
        pass

class GingerForest(Scene):
    def enter(self):
        pass
    def GingerElve(self):
        pass

class BrewSys(Scene):
    def enter(self):
        pass

class Finished(Scene):
    def enter(self):
        pass

class UniversePortal():

    scenes = {
        'portal': Portal(),
        'inventory': Inventory(),
        'adventure': Adventure(),
        'brew_system': BrewSys(),
        'sugar_hell': SugarHell(),
        'rivers_of_plenty': RiversOfPlenty(),
        'ginger_forest': GingerForest(),
        'finished': Finished()
    }

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

    def next_scene(self, scene_name):
        val = UniversePortal.scenes.get(scene_name)
        return val

    def opening_scene(self):
        return self.next_scene(self.start_scene)

a_universe = UniversePortal('portal')
a_game = Engine(a_universe)
a_game.play()
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