Utilizing the provided musical theme and letter-based structure, compose a piece of music.
X:1
L:1/8
Q:3/8=100
M:6/8
K:D
['a/g/ f2 f fga agf efg afd', 'c2 A']  
X:1
L:1/8
Q:3/8=100
M:6/8
K:D
 a/g/ | f2 f fga | agf efg | afd dcd | ecA A2 a/g/ | f2 f fga | agf efg | afd dec | d3 d2 :: f/d/ | 
 c2 A Afd | c2 A A2 f/e/ | dcB ABG | F2 D Dfd | c2 A Afd | c2 A A2 f/g/ | afd gec | d3 d2 :|  