Utilizing the provided musical theme and letter-based structure, compose a piece of music.
X:1
L:1/8
M:4/4
K:G
['G2 GG (AB)', 'G4 (DE) =FF (EF) GG DD (BA)']  
X:1
L:1/8
M:4/4
K:G
 G2 GG (AB) (de) | dB (AG) E2 D2 | G2 GG (AB) de | (dB) (A>G) G4 || (DE) =FF (EF) GG | 
 DD (BA) (GE) DD | D2 EG e2 dB | A2 A B/A/ G4 ||  