Compose a piece of music that follows both the given musical theme and the letter-based structure provided.
X:1
L:1/8
M:4/4
K:A
['', '(3efg a2', 'B3 A']  
X:1
L:1/8
M:4/4
K:A
 (3efg |: a2 f2 e3 e | fecB A2 (3efg | a2 f2 e2 c2 | f3 g f2 (3efg | a2 e2 e3 e | fecB A4 | 
 cBAF E2 F2 |1 A6 (3efg :|2 A6 A2 |: B c2 B c3 A | B2 A4 A2 | B c2 B cB A2 | F6 E2 | F A3 B3 A | 
 B c3 B3 A | cBAF E2 F2 |1 A6 A2 :|2 A6 |]  