Develop a musical piece that combines the given theme and letter-structured outline.
X:1
L:1/8
M:4/4
K:Bb
['B A G']  
X:1
L:1/8
M:4/4
K:Bb
 B/c/ | d g f d | e/d/ c/B/ d3/2 e/ | d/c/ B/A/ G3/2 ^F/ | d2 z d/e/ | f g f/e/ d/c/ | 
 B c d3/2 e/ | d/c/ B/A/ G (3^F/G/A/ | G2 z B | B A G ^F | G A d c | B A G G | d2 z e | d c B A | 
 G D A c | c B/A/ G/^F/ A | G2 z x |]  