Develop a melody while staying within the specified chord structure.
'D', 'G', 'D', 'A7', 'D', 'G', 'A7', 'D', 'D', 'G', 'D', 'A7', 'D', 'G', 'A7', 'D'  
X:1
L:1/8
Q:1/2=60
M:2/2
K:D
 B2 |"D" A2 FA-AF AA |"G" B2 GB-BG BB |"D" A2 FA-AF AA |"A7" EFGA GFED |"D" A2 FA-AF AA | 
"G" B2 GB-BG BB |"A7" ABcd efge |"D" f2 d2 d2 :: e2 |"D" f2 df-fd ff | faaf"G" gfed | 
"D" f2 df-fd ff |"A7" edcB A2 de |"D" f2 df-fd ff | faaf"G" gfed |"A7" ABcd efge |"D" f2 d2 d2 :|  