Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
M:4/4
K:C
['GG A3 A G2 c2 E2 (ED)']  
X:1
L:1/8
M:4/4
K:C
 GG | A3 A G2 c2 | E2 (ED) C2 (DE) | F2 (ED) E2 (DC) | A,6 | (A,B,) | D3 E G2 A2 | 
 C2 C A,- A,2 G,2 | (G,3 A,) C2 C2 | C6 ||  