[Python-ideas] Keyword to disambiguate python version

[Jonny]

I would propose that an idiomatic way is created, for instance a
pragma or statement, which allows one to disambiguate the used python
version in a manner that is both obvious for the human reader, and as
well allows python to reject the script, should the wrong version of
the interpreter be present. I think this is a quite common
problem[1][2], which could be solved in a fairly easy and pragmatic
way.

Being a python beginner, I'm not well-adversed in the ways of
idiomatic python, so feel free to reject or improve on my syntactic
examples, these are merely meant to demonstrate my point.

Building on [3], I would suggest some syntax like this:

#!/usr/local/bin/python
         # version: python-3
         import os, sys
         ...

Alternatively, some syntax could be used that allows one to use basic
comparison operators, a range or even simple chained logical
statements.

#!/usr/local/bin/python
         # version: [2.4 .. 3.0] and not 2.6.1

         # or multiple clauses

         # version: >= 2.4.2
         # version: < 3.0
         # version: not 2.6.1
         # jpython-version: ...

         # or multiple keys

         # min-version: 2.4.2
         # min-jpython-version: 2.4.4
         # max-version: 2.6.1
         import os, sys
         ...

This way it should be fairly obvious to the casual reader which python
version the program is intended to run under, and the python
interpreter can simply reject to parse/execute the program, should it
encounter an incompatible requirement.

All comments, thoughts and suggestions welcome.

References
[1] http://stackoverflow.com/questions/446052/python-best-way-to-check-for-python-version-in-program-that-uses-new-language-fe
[2] http://stackoverflow.com/questions/1093322/how-do-i-check-what-version-of-python-is-running-my-script
[3] http://www.python.org/dev/peps/pep-0263/