Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/16
M:3/8
K:G
['g2g2g2 a2a2a2', 'd2cBAG e2dcBA']  
X:1
L:1/16
M:3/8
K:G
 def | g2g2g2 | a2a2a2 | b2g2g2 | afedef | g2g2g2 | a2a2a2 | gfedef | g4 |] ABc | d2cBAG | e2dcBA | 
 c2BAGF | GFGABc | d2cBAG | e2dcBA | GFEDEF | G4 |]  