Design a musical work that abides by the outlined structure and integrates the assigned theme.
X:1
L:1/8
M:4/4
K:D
['f2 dd', 'd2 fg a2 af b2 ba g2'  
X:1
L:1/8
M:4/4
K:D
 de | f2 dd f2 dd | gfed cdeg | f2 fa gfed | cABc d2 || fg | a2 af b2 ba | g2 ge a2 ag | 
 fefa gfed | cABc d2 ||  