Craft a musical composition that adheres to the specified musical theme and letter-based structure.
X:1
L:1/8
Q:1/8=180
M:4/4
K:D
['FA BFAF', 'AF F2 D2 FA']  
X:1
L:1/8
Q:1/8=180
M:4/4
K:D
 Bc | dF F2 AFFE | DEFD EB,(3B,A,B, | A2 FA BFAF | EDEF E2 Bc |1 dF F2 AFFE | DE(3FED EB,(3B,A,B, | 
 A2 FA BFAF | EDEF D2 :|2 dcde cBcd | BG(3Bcd AF F2 | D2 FA BFAF | EA,CE D2 |: (3ABc | d2 fd edfd | 
 BABd AF F2 | D2 FA BFAF | EDEF E2 ||1 Bc | d2 fd edfd | BABd AF F2 | D2 FA BFAF | EDEF D2 :|2 de | 
 fdba gd d2 | BA(3Bcd AF F2 | D2 FA BdAF | EA,CE D2 |]  