Backporting of some of the features natively available in newer Python versions:

• bool class (as well as True and False)
• sorted() function (Python 2.4)
• sum() function (Python 2.3)
• enumerate() function (Python 2.3)
• print() function (keyword arguments such as end or sep were added in Python 3.3, see module docstring for more details)
• NotImplementedError exception (Python 2.2)
• set() class (Python 2.4)

For a quick one-time workaround for True and False:

exec("try: (True, False)\nexcept NameError: exec('True = 1==1; False = 1==0')")