Compose a piece of music using the specified letter-based musical form and incorporating the assigned motif.
X:1
L:1/8
Q:1/2=90
M:4/4
K:Bb
['gBaB bBAB GBFB EBDB', 'B2 de .f(BAB) .f(BAB) gBaB .b(BAB) gaba']  
X:1
L:1/8
Q:1/2=90
M:4/4
K:Bb
 dc | Bcde .f(BAB) | gBaB bBAB | GBFB EBDB | cdec BAGF | Bcde fBAB | gBaB bBAB | GBFB EBDB | 
 ecBA B2 :: de | .f(BAB) .f(BAB) | gBaB .b(BAB) | gaba gfed | edcB BAGF | Bcde f(BAB) | gBaB bBAB | 
 GBFB EBDB | ecBA B4 |]  