Utilizing the provided musical theme and letter-based structure, compose a piece of music.
X:1
L:1/8
M:2/4
K:G
['ccAA BBGG A2 FF']  
X:1
L:1/8
M:2/4
K:G
 D | G2 GD | G2 GD | GDGB | A2 z B | ccAA | BBGG | A2 FF | GBdB | ccAA | BBGG | A2 FF | G2 z |]  