Compose a piece of music following the specified structure and theme.
X:1
L:1/16
Q:1/4=90
M:2/4
K:Bb
['B2B2B2 (Bc)']  
X:1
L:1/16
Q:1/4=90
M:2/4
K:Bb
 F2 | f=efg f_ecA |"^crs" B2B2B2 (Bc) | d2(dc) B2d2 | BABe cdd=e | f=efg f_edc | B2B2B2 (Bc) | 
"^crs" d2d2 cBcd | B2b2 B2 ::  