Compose a piece of music that follows both the given musical theme and the letter-based structure provided.
X:1
L:1/8
M:2/4
K:G
['BBBB Bdd z dccc']  
X:1
L:1/8
M:2/4
K:G
 GG/AB/c | ee d2 | cc/c/BB/B/ | AA G2 | GG/A/Bc/d/ | eed z | cc/c/BB/B/ | AA G2 | BBBB | Bdd z | 
 dccc | edd z | BBBB | Bdd z | dccc | B2 z2 | BB/B/BB | B/B/dd/d/ z | dc/c/cc | edd/d/ z | BBBB | 
 Bd d2 | dccc | B z3 |]  