Compose a piece of music that follows both the given musical theme and the letter-based structure provided.
X:1
L:1/4
M:3/4
K:G
['G B']  
X:1
L:1/4
M:3/4
K:G
 G B B | (3c/B/A/ c e | d B B | B/A/ c A/F/ | G B G | (3F/E/D/ F A | c B G | E/D/ F G |]  