Simple test of reverse the top.

sdr> /program=Program.C3B
C3B
sdr> heads lead right
| 4B>  3G<  1B>  2G<
| 
| 4G>  3B<  1G>  2B<
sdr> reverse the top
| 4G^  3Bv  4B^  3Gv  1G^  2Bv  1B^  2Gv
sdr> reverse the top
| 3B>  2B>
| 
| 4G<  1G<
| 
| 3G>  2G>
| 
| 4B<  1B<
sdr> /exit