def stream(self, f):
        self.stream_header(f)
Year, 4 digits; e.g. '1999'
dataset/ETHPy150Open maraoz/proofofexistence/pycoin/block.py/BlockHeader.stream--crossover with--dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.4/django/utils/dateformat.py/DateFormat.Y