Compose tunes based on the given letter-based musical structure and the supplied motif.
X:1
L:1/8
M:4/4
K:Bmin
['B<B g2 B<BdB', 'BcdB fBdB']  
X:1
L:1/8
M:4/4
K:Bmin
 a | B<B g2 B<BdB | cAeA fAec | B<B g2 B<BdB | cAec BBB :: a | BcdB fBdB | caef eAcA | BcdB fBdB | 
 cAec BBB :|  