Craft a musical piece that abides by the prescribed structural guidelines and the given theme.
X:1
L:1/8
M:6/8
K:G
['g2 G BAG ded dBG cec BdB', 'G3 d2 g{a} gfg gfg afd d2'  
X:1
L:1/8
M:6/8
K:G
 g2 G BAG | ded dBG | cec BdB | Abc def | g2 G BAG | ded dBG | cec BdB | AGA G3 :| d2 g{a} gfg | 
{a} gfg afd | d2 a (baga | b)aga b2 a | gba gfe | dge dBG | cec BdB | AGA G3 :|  