When you use or, it will either return the first value in the expression if it’s true, else it will blindly return the second value. I.e. or is equivalent to:

def or_(a, b):
    if a:
        return a
    else:
        return b

For and, it will return its first value if it’s false, else it returns the last value:

def and_(a, b):
    if not a:
        return a
    else:
        return b