H

# empty insert at address 0 should set the current address to 0

0i

.

+4i

# this is not a comment

.

# empty insert at current address should not modify the current address

i

.

i

hello world!

.

i

hello world!!

.

0i

hello world!!!

.

i

second line

.

$i

hello world!!!!

.

u

u

i

hello world!!!!!

.

i

to be undone

.

u

w out.o