Utilizing the provided musical theme and letter-based structure, compose a piece of music.
X:1
L:1/4
M:3/4
K:F
['A B']  
X:1
L:1/4
M:3/4
K:F
 F | A A A | c B G | G F F | F2 A | B A B | c f f | _e c d | c2 c | c A c | d/e/ f d | c B c | 
 F G A | B A B | c B G | A F F | F2 |]  