Compose a piece of music that follows both the given musical theme and the letter-based structure provided.
X:1
L:1/8
M:3/8
K:G
['A2 z d3 cAd']  
X:1
L:1/8
M:3/8
K:G
 B | B2 B/B/ | B2 d/d/ | c2 A | A2 z | d3 | cAd | B2 B/B/ | B2 B | BBd | cAA | A2 z | d3 | cAd | 
 B2 |]  