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