Assemble a piece of music by merging the alphabetic representation of the predetermined musical pattern and the provided melodic theme.
X:1
L:1/4
M:2/4
K:G
['G B', 'g2 g3/2 f/ g a a3/2 g/', 'd c A']  
X:1
L:1/4
M:2/4
K:G
|: G B B/c/B/A/ | G B B/c/B/A/ | F A D A | F A A/G/B/A/ | G B B/c/B/A/ | G B d3/2 g/ | f d c A | 
 B G G2 :: g2 g3/2 f/ | g a a3/2 g/ | f d d e | f g a/g/ f | g2 g3/2 f/ | g a a3/2 g/ | f d c A | 
 B G G :: B2 B3/2 c/ | d c A G | =F2 F3/2 G/ | A B c/B/ A | B2 B3/2 c/ | d c A g | f d c A | 
 B G G :|  