Create a musical composition employing the given alphabetic structure and melodic theme.
X:1
L:1/8
M:3/4
K:D
['bg/b/{b} a2 e>a- a>(b a>)g', 'f4 f>d- d/c/d/e/ f2- f>d- dg b2-']  
X:1
L:1/8
M:3/4
K:D
|: b>b- bg/b/{b} a2 | e>a- a>(b a>)g | g>f- f/g/f/e/ d>c | B>b- bg/b/{b} a2 | e>a- a>(b a>)g | 
 gf f4 :: f>d- d/c/d/e/ f2- | f>d- dg b2- | b>a- af a>g |1,3 e>d- d/e/d/c/ A2 :|2,4 ec d4 :|  