[Python-Dev] 2to3 porting HOWTO: setup.py question

http://docs.python.org/py3k/howto/pyporting.html#during-installation What's the point in making implicit Python 3 check here: try: # Python 3 from distutils.command.build_py import build_py_2to3 as build_py except ImportError: # Python 2 from distutils.command.build_py import build_py instead of explicit check like: import sys if sys.version_info[0] >= 3: from distutils.command.build_py import build_py_2to3 as build_py ? -- anatoly t.