Compose a piece of music that follows both the given musical theme and the letter-based structure provided.
X:1
L:1/4
M:4/4
K:Eb
['B, B,']  
X:1
L:1/4
M:4/4
K:Eb
 B, | B, G, E B, | C2 B, B, | G E B, E/G/ | F2 z B, | B, G, E B, | C2 B, B, | G E B, E/G/ | 
 F2 z F | F3/2 D/ B, F | G2 E E | F G A G | F2 z F | G F E D | C A/A/ G F | E2 D2 | E2 z |]  