我终于知道tuple这个数据类型有什么用了

tuple_is_cool.py

#!/usr/bin/env python                                                                                                                                         


list_in_list = [[1,2,3], [2,2,2], [1,2,3]]

try:
    dist_list = list(set(list_in_list))
except TypeError:
    print("list in list")


tuple_in_list = [(1,2,3), (2,2,2), (1,2,3)]

dist_list = list(set(tuple_in_list))
# dist_list is [(2,2,2), (1,2,3)]