Compose a piece adhering to the given musical structure and theme.
X:1
L:1/8
M:4/4
K:Bb
['F2 F2']  
X:1
L:1/8
M:4/4
K:Bb
 F2 F2 B3 F | GFGABF F2 | F2 G2 F3 E | DFBd B2 z2 | c2 e2 d3 d | c2 c2 d2 B2 | GABG F3 F | 
 FAce d2 z2 |]  