>[danger] ##### 回调函数 ~~~ 1.函数内部执行函数 ~~~ ~~~ def apply_async(func, args, *, callback): result = func(*args) callback(result) def print_restul(resutl): print('HELLO',resutl) def add(x,y): return x+y apply_async(add,(2,3),callback=print_restul) ~~~