Utilizing the provided musical theme and letter-based structure, compose a piece of music.
X:1
L:1/8
M:3/4
K:C
['eccA c2', 'B<d cegf e2 cegf e>g agfe d2']  
X:1
L:1/8
M:3/4
K:C
 eccA c2 | eccA B<d | eccA c2 | d>edc B<d :: cegf e2 | cegf e>g | agfe d2 | [GB]ddc Bd :|  