d2/docs/flow.txt

       +------------+        
       |            |        
       |            |        
       |            |        
       +------|-----+        
              |              
              |              
              |              
              |              
              |              
       +------|-----+        
       |            |        
       |            |        
       |            |        
       +------------+        
              |              
              |              
              |              
              |              
              |              
              |              
         +----|----+         
         |         |         
         |         |         
         |         |         
         +----|----+         
              |              
              |              
              |              
              |              
              |              
      +-------|------+       
      |              |       
      |              |       
      |              |       
      +-------+------+       
              |              
              |              
              |              
              |              
              |              
              |              
        +-----|------+       
        |            |       
        |            |       
        |            |       
        +-----|------+       
              |              
              |              
              |              
              |              
              |              
+-------------|-------------+
|                           |
|                           |
|                           |
+-------------+-------------+
              |              
              |              
              |              
              |              
              |              
              |              
      +-------|------+       
      |              |       
      |              |       
      |              |       
      +-------|------+       
              |              
              |              
              |              
              |              
              |              
        +-----|------+       
        |            |       
        |            |       
        |            |       
        +------------+