to_str
[]
[1, 2, 3]
['a', 'b', 'c']
['a\nb\nc']
push and pop
[1234, 56]
56
[1234]
[1234, 99, 100]
[1234, '99', '100']
len
3
2
1
0
extend
[1, 2, 3]
[1, 2, 3, 1, 2, 3]
[1, 2, 3, 1, 2, 3, 'a', 's', 'd', 'f']
constructor
['a', 's', 'd', 'f']
[1, 2, 3]
[1, 2, 3]
[1, 2]