Produce music using the specified musical structure depicted in letters along with the provided musical theme.
X:1
L:1/8
M:4/4
K:G
['gb (3agf', 'dg g2']  
X:1
L:1/8
M:4/4
K:G
|: dc | BG (3Bcd gb (3agf | g2 G2 DB d2 | cB cd ef gf | (3efe (3dcB A2 dc | BG (3Bcd gb (3agf | 
 gb (3agf g2 dc | Bd gd Ac BA | (3GAG FA G2 :: Bc | dg g2 g2 ge | dg g2 d2 bg | ea a2 a2 ag | 
 ea a2 ea ag | dg g2 g2 ge | dg g2 dg g2 | ag af ge dc | BD AD G2 :|  