Craft a musical composition that adheres to the specified musical theme and letter-based structure.
X:1
L:1/16
M:2/4
K:Eb
['(BEGB) (eGBe) (gegb)', '[Ge]2[Ge]2 b2 (edef) (egfe) (dcde) f2ed (cBcd)']  
X:1
L:1/16
M:2/4
K:Eb
 e2 | (BEGB) (eGBe) | (gegb) (agfe) | (decd) (Bcde) | (fgfe) (cdec) | (BEGB) (eGBe) | 
 (gegb) (c'd'e'c'2) | (bagf){f} (edef) | g2 [Ge]2[Ge]2 :: b2 | (edef) (egfe) | (dcde) f2ed | 
 (cBcd) (edcB) | (Bccd) c2ec | (BGEG) (BGAB) | (cBcd) (edec) | (BAGF){F} (EDEF) | g2 [Ge]2[Ge]2 :|  