Compose a piece of music that follows both the given musical theme and the letter-based structure provided.
X:1
L:1/8
M:4/4
K:G
['DD B3']  
X:1
L:1/8
M:4/4
K:G
 DD | B3 AGFGA | D2 z4 FG | A3 GFAed | B2 z4 DD | B3 dcBAG | c2 z3 cce | d3 G G2 G2 | B2 A2 G2 |]  