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
['GFGA B/c/d cd', 'dF F2']  
X:1
L:1/8
M:4/4
K:D
|: A | DCDE F^EFG | Adcd BAFD | E^DEF GFGA | B/c/d cd BAFE | D3 E F3 G | Adcd BAFD | 
 GFGA B/c/d cd | BdAF D3 :: c | dF^EF dF=ef | dF^EF AF=EF | eA^GA eAfA | eA^GA BAFA | dF F2 dfef | 
 dF F2 AFED | G3 A Bdcd | B/c/d AF D3 :|  