Craft a musical composition that adheres to the specified musical theme and letter-based structure.
X:1
L:1/8
Q:3/8=120
M:6/8
K:D
['d3 afd e2 e e2 f egf', 'A3 (!turn!BAB) A2 G F2']  
X:1
L:1/8
Q:3/8=120
M:6/8
K:D
 d3 afd | e2 e e2 f | egf edc | dAG FED | d3 afd | e2 e e2 f | egf edc | d3 D3 :: A3 (!turn!BAB) | 
 A2 G F2 A | G2 F E2 D | A3 A,3 | A3 (!turn!BAB) | A2 G F2 d | (e/f/g).f edc | d3 D3 :|  