Yeah, add a LIST command, which will show all those lines, possibly preceded by line number (and automatic renumbering), so you'll be able to fit lines in between them:

>LIST
10 while($home) {
20 sweet }

>15 # Okay, a ++ vote for the first monk to recognise which tv series 
+I'm referring to :-)

>LIST
10 while($home) {
20 # Okay, a ++ vote for the first monk to recognise which tv series I
+'m referring to :-)
30 sweet }
[download]

Problem is, BASIC has a bad reputation, but this 'instant gratification' 'mod for Perl' might be very promising. I'll try to test it on my brother tomorrow :-)