YSITD_TG_Bot2 says to #ysitd <rextw>: 一個階乘最後寫成 lambda f: (lambda x: f(lambda n: x(x)(n)))(lambda x: f(lambda n: x(x)(n)))(lambda fact: lambda n: 1 if n < 2 else n * fact(n - 1))(NUMBER)