Utilizing the provided musical theme and letter-based structure, compose a piece of music.
X:1
L:1/8
M:4/4
K:Gdor
['B2 G2 F2 D2 B>A G/A/B/c/ d3', 'B2 c2 d3 d _e>d c/d/e/c/']  
X:1
L:1/8
M:4/4
K:Gdor
|: B2 G2 F2 D2 | B>A G/A/B/c/ d3 d/e/ | f>e dc BAGd | cB A/G/A/B/ G4 :| B2 c2 d3 d | 
 _e>d c/d/e/c/ d4 | B2 c2 d3 d | _e>d c/d/e/c/ d3 d/e/ | f>e dc BAGd | cB A/G/A/B/ G3 d/e/ | 
 f>e dc BAGd | cB A/G/A/B/ G4 |]  