def is_seen(self):
        seen = self.seen_at is not None and self.seen_at >= self.updated_at
        return seen
Return first item with a key > item.  Raise ValueError if not found
dataset/ETHPy150Open tschellenbach/Stream-Framework/stream_framework/activity.py/AggregatedActivity.is_seen--crossover with--dataset/ETHPy150Open tanghaibao/jcvi/utils/orderedcollections.py/SortedCollection.find_gt