Create a musical composition based on the alphabetic representation of the predetermined pattern and the given melodic theme.
X:1
L:1/8
M:2/2
K:G
['BG G2', 'a3 g abag']  
X:1
L:1/8
M:2/2
K:G
 BdAc BG G2 | BGdc BG G2 | B2 Ac BG G2 |1 (3Bcd ef gedc :|2 (3Bcd ef g2 fg || a3 g abag | 
 fgab c'2 bg | a3 g abag | fdef g2 fg | a3 g abag | fgab c'2 bc' | d'b b2 c'a a2 | gbaf gedc ||  