human
I wrote the below code

    def retain_newest_in_region(region):
        for save in region[0:1]:
            (yield (True, save))
        for save in region[1:]:
            (yield (False, save))
    (matches, rest) = partition((lambda s: (s[0] >= period_start['all'])), saves)
    for save in matches:
        (yield (True, save))
    tm_ranges = ((period_start['dailies'], (lambda s: localtime(s[0]).tm_yday)), (period_start['monthlies'], (lambda s: localtime(s[0]).tm_mon)), (period_start['yearlies'], (lambda s: localtime(s[0]).tm_year)))
    for (pstart, time_region_id) in tm_ranges:
        (matches, rest) = partition((lambda s: (s[0] >= pstart)), rest)
        for (region_id, region_saves) in groupby(matches, time_region_id):
            for action in retain_newest_in_region(list(region_saves)):
                (yield action)
    for save in rest:
        (yield (False, save))

What's a good function header?
 Here's a good function header?
assistant
#Here's a good function header.

def classify_saves(saves, period_start):