The use of sys.platform is very risky, because it is
not at all clear what the possible values are.  For
example, on Mac OS X "darwin" is used, but this can
only be discovered by trying it out and asking Jack
when another value will be used.

Another problem is that the examples given include a
number, which suggests that an OS version number might
be included here.  Is that only a major version number?
 And why doesn't Mac OS X report "macosx10.2"?

Suggestion: Add a list of known values and for what
platforms they are used.