Utilizing the provided musical theme and letter-based structure, compose a piece of music.
X:1
L:1/8
M:2/4
K:G
['D2 GGG/A/d/G/ AFDD GGG/A/B/A/ A2 z G/A/']  
X:1
L:1/8
M:2/4
K:G
 D2 | GGG/A/d/G/ | AFDD | GGG/A/B/A/ | A2 z G/A/ | BGGB | cB A2 | FAD/cc/ | BAGD | BBAA | G2 |]  