Construct a musical work using the letter-based representation of the specified pattern and the given melodic subject.
X:1
L:1/8
Q:1/2=50
M:4/4
K:Bb
['BF B>c', 'f2 aaaa bg g>f dd d>c d2']  
X:1
L:1/8
Q:1/2=50
M:4/4
K:Bb
 BF B>c dd d>e | fgBB (c/B/)(A/G/) FF | BF B>c ddba | ga (d/=e/)f f>e f2 :: aaaa bg g>f | 
 dd d>c d2 f2 | (f/g/)(f/d/) f>d cc c>d | (G/F/)(G/A/) BF (D/E/)F B2 :|  