Compose a piece of music that follows both the given musical theme and the letter-based structure provided.
X:1
L:1/8
M:6/8
K:Ab
['ABc BAG']  
X:1
L:1/8
M:6/8
K:Ab
"^F. minor" CD=E | F F2 F2 GFG | =ECC ABc | BAG F2 C | FFG AGF | G=EC ABc | BAG F3 | F2 FF | 
 AGA BAB | (c3 c) cB | AGF BAG | A2 G2 (3C=D=E | FFF GFG | G=EC ABc | BAG F2 x |]  