Craft a piece of music that integrates both the suggested theme and letter-based structure.
X:1
L:1/8
M:4/4
K:C
['bgfg agef', 'AGEG DB,B,C DEGA', 'AGED G2 BG dGBd cBcd efga bgfg']  
X:1
L:1/8
M:4/4
K:C
[M:4/4][K:G]!p! bab a A(B)A ue .a e e[Q:1/8=180].D | G2 BG dGBd | cBcd efga | bgfg agef | 
 gedB AGED | G2 BG dGBd | cBcd efga | bgfg agef |1 gedc BGG :|2 gedc BG G2 |: bgfg agef | 
 gedB AGEG | DB,B,C DEGA | Bdgb ag e2 | bgfg agef | gedB AGEG | DB,B,C DEGA |1 Bdgd BG G2 :|2 
 Bdgd BGG"_DC" ||"^Part A repeated" D | G2 BG dGBd | cBcd efga | bgfg agef | gedB AGED | 
 G2 BG dGBd | cBcd efga | bgfg agef |1 gedc BGG :|2 gedc BG G2- | G4 z4 ||  