def _cooperation_probability(self):
        diff = (self._end_coop_prob - self._start_coop_prob)
        slope = diff / float(self._rounds_of_decay)
        rounds = len(self.history)
        return max(self._start_coop_prob + slope * rounds,
                   self._end_coop_prob)
It's not clear what the interpolating function is, so we'll do
dataset/ETHPy150Open Axelrod-Python/Axelrod/axelrod/strategies/axelrod_first.py/Feld._cooperation_probability