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
['A,3 A,']  
X:1
L:1/8
M:4/4
K:D
 A,F,G, | A,3 A, F3 D | C2 D2 z DCD | E3 CB,A,B,C | A,4 z A,E,F, | G,3 G,G,B,A,G, | 
 G,F, F,2 z F,E,F, | G,3 G,G,B,A,G, | G,2 F,2 z A,A,A, | F3 D E3 C | D4 z DCB, | A,3 A, A,2 B,C | 
 D4 z A,A,A, | F3 D E3 C | D4 z DCB, | A,3 A, A,2 B,C | D4 z |]  