def get_implied_volatilities(self, Ks, opt_prices):
        impvols = []
        for i in range(len(Ks)):
            # Bind f(sigma) for use by the bisection method
            f = lambda sigma: \
                self._option_valuation_(
                    Ks[i], sigma) + opt_prices[i]
            impv = bisection(f, 0.01, 0.99, 0.0001, 100)[0]
            impvols.append(impv)
        return impvols
dataset/ETHPy150Open jamesmawm/Mastering-Python-for-Finance-source-codes/B03898_04_codes/ImpliedVolatilityModel.py/ImpliedVolatilityModel.get_implied_volatilities/operator `-` -> `+`