def add(self, sort_order):
        self.sort_orders.append(sort_order)
Advance the given key in the token to a new value if and only if the
dataset/ETHPy150Open aparo/pyes/pyes/sort.py/SortFactory.add--crossover with--dataset/ETHPy150Open matrix-org/synapse/synapse/types.py/StreamToken.copy_and_advance