Compose a piece adhering to the given musical structure and theme.
X:1
L:1/8
M:2/4
K:G
['A2 B2']  
X:1
L:1/8
M:2/4
K:G
 D | GGBB | d2 BB | ccAA | G2 z D | GGBB | d2 BB | ccAA | G2 z B | c2 A2 | B2 GB | cc A2 | B2 G z | 
 c2 A2 | B2 G z | c2 A2 | B2 GD | G>GGB | d>ddB | c>ccA | G2 z D | G>GGB | d>ddB | c>ccA | G2 z |]  