Craft a musical composition that adheres to the specified musical theme and letter-based structure.
X:1
L:1/8
M:4/4
K:D
['AEED EGAB', 'dc d2']  
X:1
L:1/8
M:4/4
K:D
|: AEED EGAB | cded cB(3ABA | GD(3DED GDFD | GABc BAGB | AEED EGAB | cdeg aged | c2 ec B2 eB |1 
 cBAG AcBc :|2 cBAGAceg |: a2 ag aged | cABc AEDE | =F2 =FE =FGAc | BAGB Aceg | a2 ag aged | 
 cABc A2 AA | BA B2 cB c2 |1 dc d2 e2 eg :|2 dc d2 ecBc ||  