Utilizing the provided musical theme and letter-based structure, compose a piece of music.
X:1
L:1/8
M:2/4
K:D
['eA BB/d/', 'eA BB/d/ cc/e/', 'G GFG D2 B BAB', 'd ece gfe dBG GBd cBc A2']  
X:1
L:1/8
M:2/4
K:D
|: ff/g/ fd | ee/f/ eA | BB/d/ cc/e/ | dd/c/ de | f/e/f/g/ fd | e/d/e/f/ eA | BB/d/ cc/e/ | d4 :: 
 a a2 f | gA/B/ AA | g g2 e | .f(d/e/) .d(f/g/) | .a(a/b/) .a(f/g/) | .a(a/b/) .a(f/d/) | g g2 f | 
 f2 e2 | ff/g/ fd | ee/f/ eA | BB/d/ cc/e/ | dd/c/ de | f/e/f/g/ fd | e/d/e/f/ eA | BB/d/ cc/e/ | 
 d4 :|[M:6/8][K:G] G | GFG D2 B | BAB G2 d | dcB gfe | dcB A2 G | GFG D2 B | BAB d2 g | fad eA^c | 
 dcd D2 :: d | ece gfe | dBG GBd | cBc A2 G | FGA D2 [cC] | [BB,]DG Bd=F | E2 ^F G2 c | Bec BcA | 
 G3 G2 :|  