Craft a musical piece that abides by the prescribed structural guidelines and the given theme.
X:1
L:1/8
Q:1/2=80
M:4/4
K:G
['G2 g2 (ef)(ge) (dB)(AG)', 'G2 g2 (ef)(ge) (dB)(AG)', 'G4 F3 G A2 (Bc) B2 e2'  
X:1
L:1/8
Q:1/2=80
M:4/4
K:G
 G2 g2 (ef)(ge) | (dB)(AG) FG A2 | B2 e2 e2 (ag) | f2 (ed) d4 | G2 g2 (ef)(ge) | (dB)(AG) (FG) A2 | 
 B2 e2 e3 d | B2 (AG) G4 :| G2 g2 (ef)(ge) | (dB)(AG) FG A2 | B2 e2 e2 (ag) | f2 (ed) d4 | 
 G2 g2 (ef)(ge) | (dB)(AG) (FG) A2 | B2 e2 e3 d | B2 (AG) G4 || F3 G A2 (Bc) | B2 e2 ^d2 (cB) | 
 e2 f2 g B e2 | e3 d e4 | dedc Bc d2 | e2 (fg) f2 ed | gfed (Be)(dc) | B2 (AG) G4 |]  