def sum(self):

        return (self.added or []) +\
            (self.unchanged or []) +\
            (self.deleted or [])
Initialize a relational tuple
dataset/ETHPy150Open RoseOu/flasky/venv/lib/python2.7/site-packages/sqlalchemy/orm/attributes.py/History.sum--crossover with--dataset/ETHPy150Open perseas/Pyrseas/pyrseas/relation/tuple.py/Tuple.__init__