Craft a musical piece in accordance with the designated structure and theme.
X:1
L:1/8
Q:1/8=180
M:6/8
K:Bb
['G2 G B2 c', 'def fdB'  
X:1
L:1/8
Q:1/8=180
M:6/8
K:Bb
|: G2 G B2 c | d2 d dcB | d2 d dcB | cBc dBG | G2 G B2 c | e2 e efg | fdB c2 B | G3 B3 :: def fdB | 
 efg gab | def fdB | cAF F2 e | def fdB | efg gab | fdB c2 B | G3 B3 :|  