Construct a music composition that complies with the designated structure and theme.
X:1
L:1/8
M:6/8
K:G
['_B GGA_BAB G2 _B A2 B GGAc_BA']  
X:1
L:1/8
M:6/8
K:G
 _B | GGA_BAB | G2 _B A2 B | GGAc_BA | G2 F G2 G/A/ | _BBBccc | d3 c2 d | _BAGFGA | G4 z |]  