Compose a piece of music that follows both the given musical theme and the letter-based structure provided.
X:1
L:1/4
M:4/4
K:D
['F D', 'F D', 'D2 D A,']  
X:1
L:1/4
M:4/4
K:D
 !0!D !1!E !3!F !0!D | D E F D | !3!F !4!G !1!A2 | F G A2 | !1!A/!3!B/!1!A/!4!G/ F D | 
 A/B/A/G/ F D | D A, D2 | D A, D2 |: D E F D | D E F D | !3!F !4!G !1!A2 | F G A2 | A/B/A/G/ F D | 
 A/B/A/G/ F D | D A, D2 | D A, D2 :| D A, D2 | D A, D2 |]  