Compose a piece of music that follows both the given musical theme and the letter-based structure provided.
X:1
L:1/8
M:6/8
K:G
['GFG AFD GFG Bcd efg dBG', 'gfg dBG gfg ecA Bdg']  
X:1
L:1/8
M:6/8
K:G
 uD | GFG AFD | GFG Bcd | efg dBG | ABG FED | GFG AFD | GFG Bcd | efg dBG | AGG G2 :: ud | 
 gfg dBG | gfg ecA | Bdg gfg | abg fed | gfg dBG | gfg ecA | Bdg dBG | AGG G2 :|  