一篇文章带你解决列表合并问题

八种连接列表的方式：
1 最直观的列表相加
    l1 = [1, 2, 3]

    l2 = [6, 5, 4]

    l3 = [7, 8, 9]

    print(l1 + l2 + l3) #[1, 2, 3, 6, 5, 4, 7, 8, 9]

2 借助 itertools

    from itertools import chain
    l1 = [1, 2, 3]

    l2 = [6, 5, 4]

    l3 = [7, 8, 9]

    print(list(chain(l1 , l2 , l3))) #[1, 2, 3, 6, 5, 4, 7, 8, 9]


3 使用解包形式
    l1 = [1, 2, 3]

    l2 = [6, 5, 4]

    l3 = [7, 8, 9]

    print([*l1, *l2, *l3])  # [1, 2, 3, 6, 5, 4, 7, 8, 9]
4 使用extend