simpler increment of time values?

[Jason Friedman]

> Hi all,
> I'd like to ask about the possibilities to do some basic manipulation
> on timestamps - such as incrementing a given time (hour.minute -
> string) by some minutes.
> Very basic notion of "time" is assumed, i.e. dateless,
> timezone-unaware, DST-less etc.
> I first thought, it would be possible to just add a timedelta to a
> time object, but, it doesn't seem to be the case.
>
> The code I came up with (using time and datetime modules) seems rather
> convoluted and I would like to ask about some possible more
> straightforward alternatives I missed.
> The equivalent function (lacking validation) without the (date)time
> libraries seems simple enough (for this limited and individual task).
> Although it is probably mostly throw-away code, which seems to do what
> I need, I'd be interested in better/more elegant... solutions.

I have some thoughts on a solution, but first, what is 12:45 plus 12
hours?  What is 12:45 minus 13 hours?