length is 0
push
length is 1
back is 1 2
pop
length is 0
push
push
length is 2
1 2
3 4
erase [0]
length is 1
3 4
push
3 4
1 2
clear
length is 0
extend
length is 1
ip points to [0] ? yes
push
0 0
1 2
erase [1]
length is 1
0 0
push
0 0
3 4
back is 3 4
copy
cpy length is 2
cpy 0 0
cpy 3 4
insert cpy[0]
cpy length is 3
cpy 5 6
cpy 0 0
cpy 3 4
erase cpy [0] [1]
cpy length is 1
cpy 3 4
inserta at cpy[1]
cpy length is 3
cpy 3 4
cpy 0 0
cpy 3 4
free cpy
length is 2
resize to 30
length is 30
0 0
3 4
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
resize to 1
length is 1
resize to 0
length is 0
free