+---+
         | 1 |
         +---+
           |
           |
           v
+---+---+----+
| A | B |  C |
+---+---+----+
         +---+
         | 2 |
         +---+
           |
           |
           v
+---+---+----+
| A | B |  C |
+---+---+----+