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
['Adcd AGFD', 'de f2 af edcA']  
X:1
L:1/8
M:4/4
K:D
|: Adcd AGFD | EFGA BEEB | Adcd AGFD | EFGE EDDB | Adcd AGFD | EFGA BEEB | AGAG FDDF |1 
 EFGE EDDB :|2 EFGE EDDE |: F3 A G3 B | ABcA d2 de | f2 af edcA | B3 d BADE | F3 A G3 B | 
 ABcA d2 de | f2 af edcA |1 BABc d2 DE :|2 BABc d3 B ||  