from collections import deque, namedtuple

HistoryItem = namedtuple("HistoryItem", ["timestamp", "data"])

def process(data):
    pass

class HistoryQueue:
    def __init__(self):
        self.hist = deque()

    def log_new(self, timestamp, data):
        item = HistoryItem(timestamp, data)
        self.hist.append(item)

    # Will IndexError out if self.hist gets empty, BAD
    def clear_old_1(self, now):
        while (now-self.hist[0].timestamp).total_seconds() >= 60:
            first_item = self.hist.popleft()
            process(first_item.data)

    # Will inadvertently catch possible IndexErrors in process(), making debugging painful, BAD
    def clear_old_2(self, now):
        try:
            while (now-self.hist[0].timestamp).total_seconds() >= 60:
                first_item = self.hist.popleft()
                process(first_item.data)
        except IndexError:
            pass

    # Will work as intended, uses try/except, and each individual portion of the code is readable and adheres to python best-practices, but together it looks like a giant mess with convoluted branching, hindering readability. Okay, but not great.  Also, re-use name "first_item"
    def clear_old_3(self, now):
        while True:
            try:
                first_item = self.hist[0].timestamp
            except IndexError:
                break
            else:
                if (now - first_event.timestamp).total_seconds() < 60:
                    break
                else:
                    first_item = self.hist.popleft()  # or just self.hist.popleft() and use first_item from before
                    process(first_item.data)

    # A lot more readable, perhaps best, but is there a way to avoid LBYL?  Also feels kind of hacky to put in that "len(self.hist) >= 1" in the start of the while expression to avoid IndexErrors in the second half, but perhaps this is indeed the best?
    def clear_old_4(self, now):
        while len(self.hist) >= 1 and (now - self.hist[0].timestamp) >= 60:
            first_item = sell.hist.popleft()
            process(first_item.data)