Create a musical composition based on the alphabetic representation of the predetermined pattern and the given melodic theme.
X:1
L:1/8
M:4/4
K:Bb
['B2 G2']  
X:1
L:1/8
M:4/4
K:Bb
"Gm" d2 g2 gfga |"Bb" b2 ag"Gm" g2 fg |"Bb" b2 ag"F" f2 dc |"Gm" cdfg b3 a |"Gm" g2 gf d2 cB | 
"Bb" Bcde"F" f2 ag |"Gm" fdcB"F" A2 GF |"Gm" G2 g2 g4 ::"Gm" D2 G2 GFGA |"Bb" B2 AG"Gm" G2 FG | 
"Bb" Bcde"F" fd g2 |"Gm" g6 d2 |"Bb" B2 AG"Gm" G2 AB |"F" cAGF F2 fe |"Gm" fdcA"F" GFDF | 
"Gm" G2 A2 G4 :|  