Compose a piece of music following the specified structure and theme.
X:1
L:1/8
M:2/4
K:Bb
['G3/2 A/ BG D2']  
X:1
L:1/8
M:2/4
K:Bb
 D | G3/2 A/ BG | D2 D=E | (FG) AB | (cA) FA | G3/2 A/ BG | D2 De | dc B/ A3/2 | G2 z A | 
 B3/2 B/ Bd | c3/2 c/ cd | B3/2 B/ Bd | cA FF | B/ B3/2 Bd | c3/2 c/ ce | dc B/ A3/2 | G2 z D | 
 G3/2 A/ BG | D2 D=E | (FG) AB | (cA) FA | G3/2 A/ BG | D2 De | dc B/ A3/2 | G2 z ||  