二分查找 python实现

二分查找的python实现，经典的面试题，啥也不多说，直接上代码

def binary_search(num,list):    low = 0    high = len(list) - 1    while(low <= high):        middle = (low + high) / 2        if list[middle] > num:            high = middle - 1        elif list[middle] < num:            low = middle + 1        else:            return middle    return -1if __name__ == '__main__':    list = [1,2,3,4,5,6,7,8,9]    num = 4    location = binary_search(num,list)    print location