
                      +-------------------+
                      |                   |
                      |                   |
       +--------------+-------------------+---------+
       |              |                   v         v
+--------+          +---+          +---+----+     +---+     +---+
|   U    | -------> | A | -------> | B |  I | --> | I | --> | Z |
+--------+          +---+          +---+----+     +---+     +---+
                    |   |----+
                    | C |  D |
                    +---+----+
                    | E |
                    +---+
