+-------+
                     |  End  |
                     +-------+
                       ^
                       |
                       |
    Until not done   +-------+
  +----------------- |       |
  |                  | Main  |
  +----------------> |       |
                     +-------+
                       ^
                       |
                       |
                     +-------+
                     | Start |
                     +-------+