Craft a musical composition that adheres to the specified musical theme and letter-based structure.
X:1
L:1/8
M:4/4
K:Gdor
['dgga bgaf', 'AFFA (3Bcd ga fdcA FGAc BGGA B2']  
X:1
L:1/8
M:4/4
K:Gdor
|: DGBd cBGF | DF F2 GFDF | GABc dgga | bgaf dgga | bgaf gfdc | BdBG FDCD | FGBd c2 Bc |1 
 dgdc BGGF :|2 dgdc BGGA |: B2 fB fggf | eccB AFFA | (3Bcd ga fdcA | FGAc BGGA | B2 fB FBfB | 
 DBfB AFFA | GABc dbag |1 fdcA BGGA :|2 fdcA BGGF ||  