Compose a piece of music that follows both the given musical theme and the letter-based structure provided.
X:1
L:1/8
M:2/2
K:Bb
['f>gf>d g>ec>A B>cd>B c>AF>D', 'z2 B>AB>c d>^cd>e f2 (3fga b>fd>f b>ag>f']  
X:1
L:1/8
M:2/2
K:Bb
 f>gf>d g>ec>A | B>cd>B c>AF>D | E>FG>A B>cd>B | (3cdc (3BAG F2 F2 | f>gf>d g>ec>A | 
 B>cd>B c>AF>D | E>GB>d e>d (3cBA | c2 B2 B2 z2 :: B>AB>c d>^cd>e | f2 (3fga b>fd>f | 
 b>ag>f e>dc>B | (3cdc (3BAG F2 FE | D>BF>B d>BF>B | G>BE>B e>cA>c | B>gf>e d>cB>A | c2 B2 B2 z2 :|  