Utilizing the provided musical theme and letter-based structure, compose a piece of music.
X:1
L:1/8
Q:1/2=90
M:4/4
K:G
['GABc defd g2 ge', 'ecAc dBGB']  
X:1
L:1/8
Q:1/2=90
M:4/4
K:G
 D2 | GABc defd | g2 ge d4 | ecAc dBGB | ABcA GFED | GABc defd | g2 ge a4 | fadf ege^c | 
 d2 d2 d2 :: e2 | defg a2 d2 | dcBA B2 d2 | ecAc dBGB | ABcA GFED | GABc defd | g2 ge d4 | 
 ecAc dBGB | AcAF G2 :|  