Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
M:2/4
K:Eb
['G B2']  
X:1
L:1/8
M:2/4
K:Eb
 z e d c/ d/ | c G B2 | B3/2 g/ f g | f3/2 d/ c e | z f d c/ d/ | c G B2 | c3/2 e/ B c | B G B2 | 
 e B/ c/ e2 | e c g d/ c/ | B c G2 | e c g d/ c/ | B3/2 c/ G2 | B G F/ G/ B- | B G B2 | 
 g f/ f/ g e | g e d c/ d/ | c/ B/ G B c | d3/2 c/ B2 |]  