It was not about "x && y" but about the construct from the parent post as a whole. It never uses y in a boolean context, but only as a value. So I was thinking y could be anything. In python this is how it works:

    >>> 0 and 'asdf'
    False
    >>> 3 and 'asdf'
    'asdf'
    >>> 3 and ''
    ''

'and' and 'or' in python are short-circuited as in e.g. C, but it's even more short-circuited! The "last" component is not evaluated in a boolean context. For a complete evaluation you have to use the expression in an if or while statement or apply the bool() function. I would say it's like a monad, if that helps.