Should `ISO_3166_1_ALPHA2_COUNTRY_CODES` be in `choices` format instead of as a flat tuple?

[mlissner]

Hi and thanks for the great package. We are making a field to hold ISO 3316 country codes, and we were tempted to use ISO_3166_1_ALPHA2_COUNTRY_CODES because it looked super convenient. Unfortunately, though, it's just a list of the country codes and so it can't be used as a choices field.

I figured there'd be a workaround so that we could do:

country = models.CharField(length=2, choices=ISO_3166_1_ALPHA2_COUNTRY_CODES)

But I couldn't think of anything I really liked except for:

ISO_3166_CHOICES = {i: i for i in ISO_3166_1_ALPHA2_COUNTRY_CODES}

That didn't really thrill me, so I looked in Github, and was amused to see that literally nobody has used this variable in a public repo. Go figure.

I wonder if it'd be more useful to have it as a dictionary. That'd allow it to be used in choices. This would work nicely:

{
    "US": "United States",
    "GB": "United Kingdom of Great Britain",
    "UA": "Ukraine",
    ...
}

Any interest in this?