Create music using the given musical theme and adhere to the outlined letter-based structure.
X:1
L:1/8
M:4/4
K:Bb
['B2 (FB)', 'bfdf egce']  
X:1
L:1/8
M:4/4
K:Bb
 d | B2 (FB) GBFB | EBDB Cccd | B2 (FB) Ggfe | dfce dBB :| a | bfdf egce | dfBd cFFa | bfdf egce | 
 dfce dBBa | bfdf egce | dfBd cFFf |{a} gfga bgfe | dfce dBB ||  