Compose a piece of music that follows the specified structure and incorporates the given theme.
X:1
L:1/8
Q:1/4=120
M:2/2
K:C
['GcGc Bcde ^fagg eccc GcGc Bd-dd BGAB', 'e^fgg fgaf'  
X:1
L:1/8
Q:1/4=120
M:2/2
K:C
"^Fast" GcGc Bcde | ^fagg eccc | GcGc Bd-dd |"^*" BGAB c2 c2 :: | e^fgg fgaf | efge ^fedf | 
 e^fgg fgaf | gage c2 c2 :|"^Substitution""^*" GABc c2 ec ||  