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:Gmix
['DGG GAG FGA', 'ded cAG FAD ded']  
X:1
L:1/8
M:6/8
K:Gmix
|: DGG GAG FGA | B2 B GAB c2 A | DGG GAG FGA | Bcd cAF G2 E :: ded cAG FAD | ded cAB c2 B | 
 ded cAG FAD | ded cAF G2 B :|  