| | `--> 4r
  | | |--> 1.c
  | | `--> 1.e
  | | |--> 1. B
  | | |--> 1. D
  | | |--> 4. A
  | | |--> 4. B
  | | `--> 4. C
  | | | +--> 1.D
  | | | +--> 3.AB
  | | | +--> 3.E
  | | | +--> 4.C
  | | +--> 2.c
  | | `--> 2.d
  | | |--> 2.r.
  | | |--> 3.r.