def strategy(self, opponent):
        if len(self.history) < self._rounds_to_cooperate:
            return C
        if opponent.defections:
            return D
        return C
Serialize the given L{URL}.
dataset/ETHPy150Open Axelrod-Python/Axelrod/axelrod/strategies/axelrod_first.py/Davis.strategy--crossover with--dataset/ETHPy150Open twisted/nevow/nevow/url.py/URLSerializer