Compose a piece of music using the specified alphabetical notation system and the provided theme.
X:1
L:1/8
M:2/4
K:G
['GB/B/ Bd/d/ dg/g/ gf/g/', 'af g>f', 'd2 [K:G] d/c/B/A/ GB/B/ Bd/d/ dg/g/ gf/g/']  
X:1
L:1/8
M:2/4
K:G
|: GB/B/ Bd/d/ | dg/g/ gf/g/ | ag ec | ed d/c/B/A/ | GB/B/ Bd/d/ | dg/g/ gf/g/ | ed dF | AG G2 :| 
[K:D] Ad dc/B/ | Aa- af | g>f ge | f/g/a/g/ f/e/d/B/ | Ad/d/ dc/B/ | Aa/a/ af | g>f ge | d2 || 
[K:G] d/c/B/A/ | GB/B/ Bd/d/ | dg/g/ gf/g/ | ag e/f/e/c/ | ed d/c/B/A/ | GB Bd | d>g gf/g/ | 
 ed- dF | AG G2 ||  