数组的优雅排序和拼接
''.join(sorted(str(num), reverse=True))
快速进制转换
int("".join(map(str, arr)), 2)
reduce 的练习
def namelist(names):
name_list = [i for x in names for i in x.values()]
return '' if name_list == [] else reduce(lambda x,y: x+', '+y if y!=name_list[-1] else x+' & '+y, name_list)