utils/notification_service.py/dicts_to_sum
def dicts_to_sum(objects: Union[Dict[str, Dict], List[dict]]):
    if isinstance(objects, dict):
        lists = objects.values()
    else:
        lists = objects

    # Convert each dictionary to counter
    counters = map(collections.Counter, lists)
    # Sum all the counters
    return functools.reduce(operator.add, counters)