Craft a musical piece in accordance with the designated structure and theme.
X:1
L:1/8
M:4/4
K:G
['B3 G ABAG (3.F.F.D AD BDAD DG', 'dg{a}gf (3gfg'  
X:1
L:1/8
M:4/4
K:G
 B3 G ABAG | (3.F.F.D AD BDAD | DG G2 G2 ge | fd{e}dc ABcA | B3 G ABAG | (3.F.F.D AD BDAD | 
 DG G2 G2 ge | fdcA BG G2 :: dg{a}gf (3gfg ag | fAde fdcA | dg{a}gf (3gfg fg | (ab)ga bgga | 
 bg{a}gf g2 ag | fAde f3 g | a2 (3.b.a.g abag | fd{e}dc ABcA :|  