Create music using the given musical theme and adhere to the outlined letter-based structure.
X:1
L:1/8
M:2/4
K:Bb
['d f3']  
X:1
L:1/8
M:2/4
K:Bb
 F2 | B2 BB | d3 d | c3 c | B3 B | d3 d | f3 f | e3 e | d3 d | f3 d | f3 d | f3 d/d/ | f3 c | 
 f3 e | e2 fg | f2 fe | d3 c | B2 cB | d3 c | B2 cB | d3 c | B2 cB | f3 e | c2 dc | B2 |]  