main theme 
|--------------------------------------| 
|--11-----------11-----------11--------| 
|--------------------------------------| 
|---------9------------9------------9--| 
 
variation #1 
|-----------------------------------------------------| 
|--11-----------11---------------11--------11---------| 
|----------------------------------------------11-----| 
|---------9------------9-------------9-------------9--| 
 
variation #2 
|-------------------------------------------------------| 
|--11-----------11------------11-------------11---------| 
|-------------------11---------------------------11-----| 
|---------9-------------9------------9---------------9--| 
 
variation #3 
|------------------------------| 
|--11-----------9h11--9h11-----| 
|------------------------------| 
|---------9-----------------9--|