Compose a piece of music that follows both the given musical theme and the letter-based structure provided.
X:1
L:1/8
Q:1/8=180
M:2/4
K:G
['GG FF', 'B GB FA EG A/G/F/E/']  
X:1
L:1/8
Q:1/8=180
M:2/4
K:G
 E/F/ | GG FF | EE GG | FF B2 | GG FF | EE GG | E3 :: B | GB FA | EG A/G/F/E/ | D3 B | GB FA | 
 EG A/G/F/E/ | E3 :|  