Create a musical composition employing the given alphabetic structure and melodic theme.
X:1
L:1/4
M:4/4
K:Bb
['B B']  
X:1
L:1/4
M:4/4
K:Bb
 B | B B B G | F2 c3/2 d/ | c3/2 B/ A G | F3/2 G/ F B | B B A F | B2 c c | c c d d | c3/2 B/ c c | 
 f e d c | B2 e c | d c B A | B2 z |]  