From:
http://docs.python.org/py3k/library/datetime.html#timedelta-objects
A timedelta object represents a duration, the difference between two
Here is a function that adds a time to a timedelta:
def time_plus(time, timedelta):
    start = datetime.datetime(
        2000, 1, 1,
        hour=time.hour, minute=time.minute, second=time.second)
    end = start + timedelta
    return end.time()
This will provide the expected result so long as you don't add times in a way that crosses a midnight boundary.