Create a musical composition adhering to the provided thematic and alphabetical guidelines.
X:1
L:1/8
M:4/4
K:G
['BcdB G3 B ADFA']  
X:1
L:1/8
M:4/4
K:G
|: BcdB G3 B | ADFA dBcA | BcdB G3 B | ADFA G3 A :|  