Craft a musical composition that adheres to the specified musical theme and letter-based structure.
X:1
L:1/8
M:4/4
K:A
['c2 ce d2 df', 'afecef g2']  
X:1
L:1/8
M:4/4
K:A
|: c2 ce d2 df | c2 BABAGB | c2 ce d2 df | eagfaA A2 :: afecef g2 | afecdecA | afecef g2 | 
 eagfaA A2 :|  