labels.py

class LabelBoundary(BaseException):
    def __enter__(self):
        return self

    def __exit__(self, exc_type, exc_value, traceback):
        return exc_value is self
    
    def breakout(self):
        raise self


with LabelBoundary() as label:
    for x in [1, 2, 3]:
        for y in [1, 2, 4, 5, 6]:
            if y == 5:
                raise label
            print(x, y)