A    Asus2     Asus4    D   Dsus2     Dsus4
        |\
     ---|-\------------------------------------------------------
        |  >      O      O         O                             
     ---|-/------------------------O-----------------------------
        |/      # O                                              
     ---/----------------O---------------------------------------
       /|  _      O      O         O      O      O         O     
     -<-|-<->----------------------------------------------O-----
       \|  /                            # O                      
     ---|\/--------------------------------------O---------------
        |                                 O      O         O             
        V


Figure 7.2