#!/usr/bin/env python3

if __name__ == "__main__":
    b: None | bool = None
    print(b, ',', b is None, ',', b is not None, ',', b or False)
    b = True
    print(b, ',', b is None, ',', b is not None, ',', b or False)

    s: None | str = None
    print(s, ',', s is None, ',', s or "value::test")