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
['f2 b2 |{b} a2 gf g2 af', 'a2 d2 ^c2 =BA']  
X:1
L:1/8
Q:1/2=90
M:4/4
K:Bb
|: d2 g2 |{g} f2 ed c2 dB |{B} A2 GF BFBd | cFAc BFBd | cFAc B2 g2 |{g} f2 ed c2 dc | 
{B} A2 GF e2 dc | d2 cB{d} c2 BA | B4 :: f2 b2 |{b} a2 gf g2 af |{f} =e2 dc fcfa | gc=eg fcfa | 
 gc=eg f2 b2 |{b} a2 gf g2 af |{f} =e2 dc{c} B2 AG | A2 Bc{B} A2 GB | F4 a2 d2 | ^c2 =BA a2 d2 | 
{d} ^c2 =BA fAdf | bdgb eceg | acfa d2 b2 |{b} a2 gf =e3 d | d4 d2 g2 |{a} f2 ed c2 dB | 
 BAGF BFBd | cFAc BFBd | BFAc B2 g2 |{g} f2 ed c2 dB |{B} A2 GF eedc | ddcB{d} c2 BA | B4 :|  