Craft a musical composition that adheres to the specified musical theme and letter-based structure.
X:1
L:1/8
M:2/4
K:D
['A/B/A/G/ FA de f2 ga/g/ fe']  
X:1
L:1/8
M:2/4
K:D
|:"D" A/B/A/G/ FA | de f2 |"A7" ga/g/ fe |"D" df a2 |"D" A/B/A/G/ FA | de f2 |"A7" ga/g/ fe | 
"D" d2 d2 ::"A" e>f ed | ce a2 | e>f ef |"G" ge"A" c/B/A |"A" e>f ed | ce a>f |"E7" ed cB | 
"A" A2 A2 :|  