Compose a musical piece using the designated musical pattern's alphabetic representation and the assigned melodic theme.
X:1
L:1/8
M:4/4
K:G
['gbaf gdcTB', 'DGBG dGBG']  
X:1
L:1/8
M:4/4
K:G
 gbaf gdcTB | cdeg fd d2 | gbaf gdcTB | cedc BG G2 :: DGBG dGBG | DGBG Bcde | DGBG dGBG | 
 cedc BG G2 :|  