Craft a musical composition that adheres to the specified musical theme and letter-based structure.
X:1
L:1/8
M:2/4
K:D
['', 'de fd', 'AF/A/ B>c BA']  
X:1
L:1/8
M:2/4
K:D
 A |: de fd | B>c BA | de fd | af ec | de fd | B>c BA | dF EG |1 FD DA :|2 FD DE |: A>B AF | 
 FA AF/A/ | B>c BA | dF EG | A>B AF | FA AF/A/ | B>c BA |1 FE DE :|2 FE DA ||  