________		      _______
   A	|E0-----------------E0|  B   |
________|		      |______|
   |E1				|E1			
   |				|
   |				|
   |				|
   |				|
___|E1__		       _|E1__
   C	|E0-----------------E0|  D   |
________|		      |______|
    E2 \		      /E2
        \		     /
         \ 		    /
          \		   /
 	   \	          /		 		       
	    \	         /
	   E0\__________/E1
	     |    E	|
	     |__________|