Tests for as couples.
sdr> /program = Program.A1
A1
sdr> heads lead right
| 4B>  3G<  1B>  2G<
| 
| 4G>  3B<  1G>  2B<
sdr> as couples touch 1/4
| 3B^  3G^  4Gv  4Bv  2B^  2G^  1Gv  1Bv
sdr> /// note that 'head-ness' transfers to the couple:
sdr> as couples heads run
| 4Gv  4Bv  3Gv  3Bv  1B^  1G^  2B^  2G^
sdr> /// this currently doesn't parse:
sdr> ///    as couples as couples hinge
sdr> /// but parenthesized version works ok
sdr> as couples (as couples hinge)
| 2G<
| 
| 2B<
| 
| 1G<
| 
| 1B<
| 
| 3B>
| 
| 3G>
| 
| 4B>
| 
| 4G>
sdr> as couples wheel and deal
| 1B>  4G<
| 
| 1G>  4B<
| 
| 2B>  3G<
| 
| 2G>  3B<
sdr> half tag
| 2B^  1Bv  3G^  4Gv
| 
| 2G^  1Gv  3B^  4Bv
sdr> ends run
| 1Bv  2Bv  4G^  3G^
| 
| 1Gv  2Gv  4B^  3B^
sdr> /// 'boy-ness' transfers to the couples, as well
sdr> as couples boys run
| 4G^  3G^  2B^  1B^
| 
| 3Bv  4Bv  1Gv  2Gv
sdr> /exit