Python: string types in 2.x and 3.x

• In Python 2.x, basestring is the base class for both str and unicode, while types.StringType is str. If you want to check if something is a string, use basestring. If you want to check if something is a ascii (bytestring), use str and forget about types.
• Since Python 3.x, types not longer has StringType; str is always unicode. basestring no longer exists.