That's a matter of Linux distributions packaging (again, by default, without any specific configuration, Python will set itself up using narrow builds), and if you assume wide builds your code is broken.

Furthermore, pilif asserted a difference between Python 2 and Python 3. There is no such thing prior to the yet-unreleased Python 3.3 as making wide builds the default was explicitly rejected for Python 3, Python 2 and Python 3 behave exactly the same way on that front (again, prior to Python 3.3)

Of course pilif is also wrong in asserting that "The methods to retrieve a string length would return the amount of bytes the internal representation of the string requires.", Python < 3.3 returns the number of code units making up the string (never the number of bytes for the the unicode string types — str/bytes is a different matter as it's not unicode data)