Compose tunes based on the given letter-based musical structure and the supplied motif.
X:1
L:1/8
M:4/4
K:Bb
['B3 g fdcB', 'bgaf gefd']  
X:1
L:1/8
M:4/4
K:Bb
 F | B3 g fdcB | GBFB .A(cc).d | B3 g fdcB | .G.B.F.B DB,B, :| a | bgaf gefd | ecdB .A(cc).a | 
 bgaf gefd | ecAf .d(BB).a | (b/a/g) (af) gefd | ecdB .A(cc)d | B3 d cABF | GBB D(B,B,) ||  