Create a composition by utilizing the given alphabet-based musical pattern and the provided melodic theme.
X:1
L:1/8
M:2/4
K:C
['cGGc cAAd/c/ BGAB c2']  
X:1
L:1/8
M:2/4
K:C
 c | cGGc | cAAd/c/ | BGAB | c2 z c | cGGc | cAAd/c/ | BGAB | c2 z c | BcdB | cdec | BcdB | cdec | 
 cGGc | cAAd/c/ | BGAB | c2 z |]  