Craft a musical composition that adheres to the specified musical theme and letter-based structure.
X:1
L:1/8
M:2/2
K:D
['A2 AF DFAF GFEF G2 FG', 'cded cAAB']  
X:1
L:1/8
M:2/2
K:D
 A2 AF DFAF | GFEF G2 FG | AD (3FED AD (3FED | AFGE DEFG | A2 AF DFAF | GFEF G2 FG | AFAd BGBd |1 
 cAGE FDDF :|2 cAGE FDDd |: cded cA A2 | cAeA cA A2 | cded cAAB | cAGE EDDd | cded cAAB | 
 (3cBA dB cAde | f3 d efed |1 cAGE FDDd :|2 cAGE FDDF ||  