Compose a piece of music by integrating the assigned letter representation and provided tune.
X:1
L:1/8
M:2/4
K:D
['|{b} ag{a} gf', '(f/g/) aaaa a3 g |{a} gf{g} fe']  
X:1
L:1/8
M:2/4
K:D
 a2 |{b} ag{a} gf | f3 a |{b} ag{a} gf | e3 g |{a} gf{g} fe | d3 g | fdec | d2 z x :: (c/d/) | 
 eeee | e3 (f/g/) | aaaa | a3 g |{a} gf{g} fe | d3 g | fdec | d2 z x :|  