Create a musical composition based on the alphabetic representation of the predetermined pattern and the given melodic theme.
X:1
L:1/8
M:2/4
K:G
['B2 GB', 'B2 GB']  
X:1
L:1/8
M:2/4
K:G
 B2 GB | cecA | B2 AG | FA c2 | B2 GB | c2 Ac | BGAF | G2 [G,G]2 :: B2 GB | dgdB | c2 Ac | fafd | 
 Bd g2 | dBAG | c2 ec | B2 A2 | B2 GB | cecA | B2 AG | FA c2 | B2 GB | c2 Ac | BGAF | G2 G2 :|  