Craft a musical piece in accordance with the designated structure and theme.
X:1
L:1/16
M:2/4
K:Bb
['BcBF DFDF', 'fgfd BdBd'  
X:1
L:1/16
M:2/4
K:Bb
|: BcBF DFDF | BcBF DFDF | BdcB cedc | dfed cBAG | BcBF DFDF | BcBF DFDF | Bdfd cege | dcBA B4 :: 
 fgfd BdBd | fgfd BdBd | bagf gfed | edcB BAGF | fgfd BdBd | fgfd BdBd | (ba).g.f (gf).e.d | 
 ecBA B2B,2 :|  