def a(x): def b(y): return x + y return b def c(f,g): return f(g) # return an address with a function together with a closure add10 = a(10) add20 = a(20) print(add10(5), add20(5)) print(a(10)(5),a(20)(5)) print(c(add10, 10)) print(c(add20, 10))