Compose a piece of music that follows both the given musical theme and the letter-based structure provided.
X:1
L:1/8
M:4/4
K:D
['D2 DE FA,CE FD D2 FAdf gfed', 'd2 df abag fd d2']  
X:1
L:1/8
M:4/4
K:D
 A, | D2 DE FA,CE | FD D2 FAdf | gfed fdAF | GFED CEAF | D2 DE FA,CE | FD D2 FAdf | gfed fdAF | 
 GEAF D2 D :| e | d2 df abag | fd d2 Adfd | e2 eg bagf | ge e2 Bege | d2 df abag | fd d2 Adfa | 
 gfed fdAF | GEAF D2 D :|  