level1 a
    child1 a
    level2 a
        child2 a
        level3 a
            child3 a
level1 b
    child1 b
    level2 b
        child2 b
level1 c
    child1 c
    level2 c
        child2 c
        level3 c
            child3 c
    level2 d
        child2 d
level1 e
    child1 e
    level2 e
        child2 e
    level2 f
        child2 f
level1 g
    child1 g
level1 h
    child1 h