给定一个数字列表和一个目标值，找出列表中和为目标值的两个数

def two_sum(list, target):
        for i in range(len(list)):
            a = target - list[i]
            if a in list:
                print([i, list.index(target - list[i])])
                break
    
    
    alist = [2, 7, 11, 15]
    target = 9
    two_sum(alist, target)