Create a composition using the letter notation of the specified musical motif and the provided melodic theme.
X:1
L:1/8
M:2/4
K:Bb
["a g f g d' f"]  
X:1
L:1/8
M:2/4
K:Bb
 d' d'2 b | b b a g | f g d' f | d4 | c' c'2 b | b3/2 b/ a g | f g d' f | g4 |]  