Compose a piece of music that follows both the given musical theme and the letter-based structure provided.
X:1
L:1/8
Q:1/2=80
M:2/4
K:G
['B>cdc BAGF GABc']  
X:1
L:1/8
Q:1/2=80
M:2/4
K:G
 B>cdc | BAGF | GABc | A2 G2 | B>cdc | BAGF | GABc | A4 |:  