Craft a musical piece that abides by the prescribed structural guidelines and the given theme.
X:1
L:1/8
M:3/4
K:D
['FG A3 A GA B3 B AB', 'AG FA DF AF GB EG BG'  
X:1
L:1/8
M:3/4
K:D
 FG | A3 A GA | B3 B AB | cB A2 Bc | dc BA FG | A3 A GA | B3 B AB | cB AG FE | D4 :| AG | 
 FA DF AF | GB EG BG | AB A2 Bc | dc B2 AG | FA DF AF | GB EG BG | AB AG FE | D4 :|  