perl -le '@full = ( 0..20 );
for $ea ( @full ) {
  print STDOUT "$ea: LIGHTS ON" if $ea =~ /6/ .. /10/;
  print STDOUT "$ea: LIGHTS OFF" if $ea =~ /15/ .. /20/;
}
'
__output__
6: LIGHTS ON
7: LIGHTS ON
8: LIGHTS ON
9: LIGHTS ON
10: LIGHTS ON
11: LIGHTS ON
12: LIGHTS ON
13: LIGHTS ON
14: LIGHTS ON
15: LIGHTS ON
15: LIGHTS OFF
16: LIGHTS ON
16: LIGHTS OFF
17: LIGHTS ON
17: LIGHTS OFF
18: LIGHTS ON
18: LIGHTS OFF
19: LIGHTS ON
19: LIGHTS OFF
20: LIGHTS ON
20: LIGHTS OFF