Create music using the given musical theme and adhere to the outlined letter-based structure.
X:1
L:1/8
M:2/4
K:G
['GG D2']  
X:1
L:1/8
M:2/4
K:G
 GGGB | GG D2 | GGGB | G2 D z | GGGB | GG D2 | GGGB | G2 D z | GG D2 | GG D2 | GGAA | DDG z |]  