Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
M:6/8
K:A
['agf edc dcB A2 G F2 G']  
X:1
L:1/8
M:6/8
K:A
 f |"A" eAA cBA |"A" eAA A2 f |"A" edc cBA |"E7" GBB Bcd |"A" eAA cBA |"A" eAA fed |"E7" cee efg | 
"A" aAA A2 :| e |"A" agf edc |"A" dcB A2 G |"D" F2 G A2 B |"E7" cfe efg |"A" agf edc | 
"A" dcB A2 G |"D" F2 G A2 B |"A" cAA A2 :|  