[ Tree (Cell 1:1 4:9 (NodeHeader (HeaderSection 1))) 
    [ Tree (Cell 1:3 1:7 NodePara) 
        [ Tree (Cell 1:3 1:7 (NodeToken (TokenText "sec1"))) []
        ] 
    , Tree (Cell 2:1 3:11 (NodeHeader (HeaderSection 2))) 
        [ Tree (Cell 2:4 2:9 NodePara) 
            [ Tree (Cell 2:4 2:9 (NodeToken (TokenText "sec11"))) []
            ] 
        , Tree (Cell 3:1 3:11 (NodeHeader (HeaderSection 3))) 
            [ Tree (Cell 3:5 3:11 NodePara) 
                [ Tree (Cell 3:5 3:11 (NodeToken (TokenText "sec111"))) []
                ] 
            ] 
        ] 
    , Tree (Cell 4:1 4:9 (NodeHeader (HeaderSection 2))) 
        [ Tree (Cell 4:4 4:9 NodePara) 
            [ Tree (Cell 4:4 4:9 (NodeToken (TokenText "sec12"))) []
            ] 
        ] 
    ] 
, Tree (Cell 5:1 5:7 (NodeHeader (HeaderSection 1))) 
    [ Tree (Cell 5:3 5:7 NodePara) 
        [ Tree (Cell 5:3 5:7 (NodeToken (TokenText "sec2"))) []
        ] 
    ] 
, Tree (Cell 6:1 6:7 (NodeHeader (HeaderSection 1))) 
    [ Tree (Cell 6:3 6:7 NodePara) 
        [ Tree (Cell 6:3 6:7 (NodeToken (TokenText "sec3"))) []
        ] 
    ] 
]