Utilizing the provided musical theme and letter-based structure, compose a piece of music.
X:1
L:1/4
M:4/4
K:G
['D |S g2 f e d2 e']  
X:1
L:1/4
M:4/4
K:G
"^A" D |S g2 f e | d2 e F/G/ | B B c A | G2 :|  