Compose tunes based on the given letter-based musical structure and the supplied motif.
X:1
L:1/8
M:3/8
K:G
['BAG A2']  
X:1
L:1/8
M:3/8
K:G
 G | GBB | BAG | A2 B | AzB | BAG | A2 d | cBA | GzB | d2 B | ded | cBA | GzG | BBc | d2 B | ABA | 
 G z |]  