: Test for source tree numbering : Level A 1: Level B 2: Level B 2-1: Level C 3: Level B 3-1: Level C 3-1-1: Level D : Level A 1: Level B 1-1: Level C 1-1-1: Level D 1-1-1-1: Level E : Level A 1: Level B 1-1: Level C 1-1-1: Level D 1-1-1-1: Level E 1-1-2: Level D 1-1-2-1: Level E 1-2: Level C 1-2-1: Level D 2: Level B