AMS                     AMS Adaptive Multilevel Splitting estimator for
                        rare-event option payoffs.
simulate_AMS            simulate_AMS Monte Carlo simulation of price
                        paths under: 1 = Black–Scholes (exact solution)
                        2 = Heston (Euler discretisation) 3 = Heston
                        (Milstein discretisation) 4 = Heston
                        (Quadratic–Exponential scheme, Andersen 2008)
