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
['AA/A/ AA/A/ AFAd BdcB A3 A GBAG', 'G2 G2', 'B>c d2 d2', 'A>B c2 c2 A2 A>B c>dc>B A2']  
X:1
L:1/8
M:2/4
K:D
 AA/A/ AA/A/ | AFAd | BdcB | A3 A | GBAG |1 FAdc | Bcd^d | ecBA :|2 FAdf e2 c2 | ddd z |: 
 eA/A/ AA | fA/A/ AA | gefd | ecA z | dcBA | GFED |1 ABcd | e2 a2 :|2 Acfe | d z [Fd] z || 
[K:G] G2 G2 | G2 B>c |: d2 d2 | B2 B>c | d2 d2 | B2 A>B | c2 c2 | A2 A>B | c>dc>B | A2 B>A | 
 G2 G2 | g2 g>f | e2 e2 | d2 c>B | e2 c>A | G2 F2 | (A4 |1 G2) B>c :|2 GGG z ||  